开关电源 外文文献

毕业设计论文外文文献翻译基于PLC双电源开关设计外文翻译中英文对照英文题目 Based on PLC dual power switch design 中文题目基于PLC双电源开关设计系 (院) 自动化系专业电气自动化技术滨州学院专科毕业设计(外文翻译)Intelligent double power1 Intelligent dual power supply switching technologyIn this paper, the double load - dual power automatic switching of PLC control, PLC control program to replace relay logic control circuits, it has the three-phase power supply phase detection and protection switching function, power returned to normal after the automatic reverse switch, when a fault and restore normal respectively sends out two difference clear alarm and prompt sound. Double load - dual power automatic switching control of PLC, the open-phase protection mainly adopts the technical proposal that : setting the three-phase open-phase detection signal circuit, the three-phase open-phase detection signal circuit directly from the main circuit of three-phase power supply, namely the intermediate relay KA1-KA3 and KA4-KA6, respectively connected to power supply main loop U1 and U2 A, B and C single phase circuit, KA1-KA3 and KA4-KA6 normally open contacts respectively as PLCinput signal, namely as the preparation of PLC U1 and U2 three-phase open-phase detection logic control program input conditions. With short phase protection double load - dual power automatic switching control, not only has the open-phase protection, but also has a short circuit and overload protection, under-voltage protection function; automatic phase lack detection, three-phase current display, a road power supply circuit can automatically switch to another power source to load power supply, light and sound alarm; in the power supply return to normal after automatic reverse switch; in the event of a failure and return to normal when respectively sends out two difference obvious alarm and prompt sound effects. It overcomes the shortcomings of low double power supply switching control system without phase protection, can automatically reverse switch, as well as fault and return to normal when using asingle audio prompts defects. The control system has perfect function, reliable performance, simple circuit structure, low manufacturing cost etc...2 Intelligent dual power supplies switching main circuit controlWith short phase protection double load - dual power automatic switching control circuit. It includes a main circuit and three-phase short signal detecting sampling circuit. The main circuit of the input power supply power supply U1 and U2, its output has two2滨州学院专科毕业设计(外文翻译)loads W1 and W2. Power main circuit of AC contactor U1 through KM1 main contacts and a load of W1 connected; power supply U2 main circuit through the AC contactor KM2 main contacts and a load of W2 connected; under the control of a control circuit, a power failure occurs, the AC contactor lost the first electrically disconnected, so that the load of detachment faults power supply circuit, the AC contactor KM3 main contact closing conduction contact loop, will be connected to the fault loop load switch automatically to another normal power supply continues to supply. Power supply U1 and U2 main circuit input end of the automatic switch in QF1 and QF2 is the primary role of overload protection and short-circuit protection; two phase power supply main loop in each phase are current meter to indicate the phase current status, with the control circuit of phase lack detection. The three-phase open-phase detection signal sampling circuit, the phase detection signal directly from the main circuit of three-phase power supply, namely the intermediate relay KA1 ~ KA3KA4 ~ KA6 are respectively connected to the power supply main loop U1 and U2 A, B phase and C phase of the single-phase circuit, KA1 ~ KA3 and KA4 ~ KA6 normally open contact as U1 and U2 three-phase open-phase detection switch sampling signal, to the PLC input terminal. Considering the PLC relay output point load capacity, through the contactor KM01 ~ KM03 to drive high current contactor KM1 ~ KM3.For three-phase power U1 A, B phase and C phase lack detection, the use of an intermediate relay KA1, KA2 and KA3, respectively connected topower the U1 main circuit A, B phase and C phase and zero line N constitute a single-phase circuit, the formation of A1, B1 and C1 phase detection circuit. The normally open contact of KA1 ~ KA3 as U1 three-phase.Phase lack detection switch sampling signal, to the PLC input terminal, used in the preparation of PLC U1 three-phase open-phase detection logic control program input conditions; similarly, the three-phase power supply U2 A, B phase and C phase lack detection, but also the use of an intermediate relay KA4, KA5 and KA6, respectively connected to power the U2 main circuit A2, B2 phase and C2 phase and zero line N constitute a single-phase circuit, the formation of A2, B2 and C2 three-phase open-phase detection circuit. KA4 ~ KA6 normally open contacts respectively as U2 three-phase open-phase detection switch sampling signal, to the PLC input terminal, used in the3滨州学院专科毕业设计(外文翻译)preparation of PLC U2 three-phase open-phase detection logic control program input conditions.3 With PLC intelligent dual power controlThe three-phase open-phase detection signal sampling circuit, as U1 and U2 three-phase open-phase detection switch sampling signals of KA1-KA3 and KA4-KA6, the normally open contacts respectively for the input of the PLC X0-X2, X3-X5. In the PLC ladder diagram program, auxiliary relay R1 as the three-phase power supply of U1 three-phase open-phasedetection, which is normally open input conditions for X0, X1 and X2" and" logic; similarly, internal intermediate relay R2 as the three-phase power supply of U2 three-phase open-phase detection, it’s on conditions for the normally open input X3, X4 and X5" and" logic.In automatic switching control process, PLC ladder diagram procedure of auxiliary relay R1 and R2 respectively controlled AC contactor KM1 ( Y0 ) and KM2 ( Y1 ) coil and electric state, directly reflects two three-phase power supply U1 and U2 respectively the total phase condition, namely, either U1 or U2 three-phase power supply phase, KM1 ( Y0 ) or KM2 ( Y1 ) will immediately loses electricity, the normally closed contact of the alternating current contactor closed KM3 ( Y2 ) control coil gets electricity to attract, through the KM3 main contacts closed conduction contact loop, will be connected to the fault circuit load W1 or W2 automatically switches to a normal power supply U2 or U1 to power supply, so as to realize open-phase protection automatic switching. In automatic switching control process, auxiliary relay R1 and R2 main function is: when troubleshooting, three-phase power U1 orU2 recover the normal power supply, R1 (or R2) have electricity, the normally closed contact action, R3 reset, cut KM3 (Y2), then KM1 (Y0) or KM1 (Y1) complex have electricity, thereby automatically reverse switching back to the power supply to load W1 U1, U2 W2 power supply to load the normal power supply state.The control circuit adopts electric whistle (or buzzer) as an alarm sound (at) the same time with the red signal (at the same time with thered signal lamp), and returned to normal when the bell HA as prompt sound. Can produce two distinct alarms and prompt sound effects.4滨州学院专科毕业设计(外文翻译)智能双电源1 智能双电源切换的技术方案本文所述的双负载—双电源自动切换的PLC控制,用PLC控制程序取代继电器逻辑控制电路,其具有对三相供电电源的缺相检测及保护切换功能,在电源恢复正常后能自动进行反切换,当发生故障和恢复正常时能分别发出两种区别明显的报警和提双负载—双电源自动切换的PLC控制,其缺相保护主要采取的技术方案是:示音响。

《功率因数校正开关电源的研究与设计》外文翻译Switching Power Supply Design(开关电源设计)CHAPTER 3Half- and Full-BridgeConverter Topologies3.1 IntroductionHalf-bridge and full-bridge topologies stress their transistors to a voltage equal to the DC input voltage not to twice this value, as do the push-pull, single-ended, and interleaved forward converter to pologies. Thus the bridge topologies are used mainly in offline converters where supply voltage would be more than the switching transistors could safely tolerate. Bridge topologies are almost always used where the normal AC input voltage is 220 V or higher, and frequently even for 120-V AC inputs.An additional valuable feature of the bridge topologies is that primary leakage inductance spikes (Figures 2.1 and 2.10) are easily clamped to the DC supply bus and the energy stored in the leakage inductance is returned to the input instead of having to be dissipated in a resistive snub -ber element.3.2 Half-Bridge Converter Topology3.2.1 Basic OperationHalf-bridge converter topology is shown in Figure 3.1. Its majoradvantage is that, like the double-ended forward converter, it subjects the “off” transistor to only V dc and not twice that value. Thus it is widely used in equipment intended for the European market, where the AC input voltage is 220 V. First consider the input rectifier and filter in Figure 3.1. It is used universally when the equipment is to work from either120-VACAmerican power or 220-V AC European power. The circuit always yields roughly320-V rectified DC voltage, whether the input is 120 orFIGURE 3.1 Half-bridge converter. One end of the power transformer primary is connected to thejunction of filter capacitors C1, C2 via a small DC locking capacitor Cb . The other end is connected to the junction of Q1, Q2, which turn “on” and “off” on alternate half cycles. With S1 in the closed position, the circuit is a voltage doubler ; in the open position, it is a full-wave rectifier. In either case, the rectified output is about 308 to 336 V dc.220 V AC. It does this when switch S1 is set to the open position for220-V AC input, or to the closed position for 120-V AC input. The S1 component is normally not a switch; more often it is a wire link that is either installed for 120 V AC, or not for 220 V AC.With the switch in the open 220-V AC position the circuit is a full wave rectifier, with filter capacitors C1 and C2 in series. It produces a peak rectified DC voltage of about (1.41×220) −2 or 308 V. When the switch is in the closed 120-V AC position , the circuit acts as a voltage doubler. One half cycle of the input voltage when A is positive relativeto B, C1 is charged positively via D1 to a peak of (1.41 ×120) −1 or 168 V. On a half cycle when A is negative with respect to B, capacitor C2 is charged positively via D2 to 168 V. The total voltage across C1 and C2 in series is then 336 V. It can be seen in Figure 3.1 that with either transistor “on,” the “off” transistor is subjected to the maximum DC input voltage and not twice that value. Since the topology subjects the “off” transistor to only Vdc and not 2Vdc, there are many inexpensive bipolar and MOSFET transistors that can support the nominal 336 DC V plus 15% upper maximum of 386 V. Thus the equipment can be used with either 120- or 220-V AC line inputs by making a simple switch or linkage change.Assuming a nominal rectified DC voltage of 336 V, the topology works asfollows: For the moment, ignore the small series blocking capacitor Cb . Assume the bottom end of Np is connected to the junction of C1 and C2. Then if the leakages in C1, C2 are assumed to be equal, that point will be at half the rectified DC voltage, about 168 V. It is generally good practice to place equal bleeder resistors across C1 and C2 to equalize their voltage drops. Now Q1 and Q2 conduct on alternate half cycles. When Q1 is “on” and Q2 “off” (Figure 3.1), the dot end of Np is 168 V positive with respect to itsno-dot end, and the “off” stress on Q2 is only 336 V. When Q2 is “on” andQ1 “off,” the dot end of Np is 168 V negative with respect to its no-dot end and the emitter of Q1 is 336 V negative with respect to its collector.This AC square-wave primary voltage produces full-wave squareWave-shapes on all second-aries—exactly like the secondary voltages in the push-pull topology. The selection of secondary voltages and wire sizes and the output inductor and capacitor proceed exactly as for the push-pull circuit.3.2.2 Half-Bridge Magnetics3.2.2.1 Selecting Maximum “On”Time, Magnetic Core,and Primary TurnsIt can be seen in Figure 3.1, that if Q1 and Q2 are “on” simultaneously—even for a very short time—there is a short circuit across the supply voltage and the transistors will be destroyed. To make sure that this does not happen, the maximum Q1 or Q2 “on” time, which occurs at minimum DC supply voltage, will be set at 80% of a half period. The secondary turns will be chosen so thatthe desired output voltages are obtained with an “on” time of no more than 0.8T/2. An “on”-time clamp will be provided to ensure that the “on” time can never be greater than 0.8T/2 under fault or transient conditions.The core is selected from the tables in Chapter 7 mentioned earlier. These tables give maximum available output power as a function of operating frequency, peak flux density, core and iron areas, and coil current density.With a core selected and its iron area known, the number of primary turns is calculated from Faraday’s law (Eq. 1.17) using the minimum primary voltage (Vdc/2) −1, and the maximum “on” time of 0.8T/2. Here, the flux excursion dB in the equation is twice the desired peak flux density (1600 G below 50 kHz, or less at higher frequency), because the half-bridge core operates in the first and third quadrants of its hysteresis loop—unlike the forward converter (Section 2.3.9), which operates in the first quadrant only.3.2.2.2 The Relation Between Input Voltage,Primary Current, and Output PowerIf we assume an efficiency of 80%, thenPin = 1.25PoThe input power at minimum supply voltage is the product of minimum primary voltage and average primary current at minimum DC input. At minimum DC input, the maximum “on” time in each half period will be set at 0.8T/2 as discussed above, and the primary has two current pulses of width0.8T/2 per period T. At primary voltage Vdc/2, the input power is 1.25Po = (Vdc/2)( Ipft)(0.8T/T),where Ipft is the peak equivalent flat-topped primary current pulse. ThenIpft (half bridge) = 3.13P0/Vdc(3.1)3.2.2.3 Primary Wire Size SelectionPrimary wire size must be much larger in a half bridge than in a push-pull circuit of the same output power. However, there are two half primaries in the push-pull, each of which has to support twice the voltage of the half-bridge primary when operated from the same supply voltage. Consequently, coil sizes for the two topologies are notmuch different. Half-bridge primary RMS current isIrms = Ipftand from Eq. 3.1Irms = 2.79Po/Vdc (3.2)At 500 circular mils per RMS ampere, the required number of circular mils is Circular mils needed = 500 ×2.79Po/Vdc= 1395Po/Vdc (3.3)3.2.2.4 Secondary Turns and Wire Size SelectionIn the following treatment the number of secondary turns will be selected using Eqs. 2.1 to 2.3 for Ton = 0.8T/2, and the term Vdc –1 will be replaced by theminimumprimary voltage, which is (Vdc/2)−1. The secondary RMScurrents and wire sizes are calculated from Eqs. 2.13 and 2.14, exactly as for the full-wave secondaries of a push-pull circuit.3.2.3 Output Filter CalculationsThe output inductor and capacitor are selected using Eqs. 2.20 and 2.22 as in a push-pull circuit for the same inductor current ramp amplitude and desired output ripple voltage.3.2.4 Blocking Capacitor to AvoidFlux ImbalanceTo avoid the flux-imbalance problem discussed in connection with the push-pull circuit (Section 2.2.5), a small capacitor Cb is fitted in series with the primary as in Figure 3.1. Recall that flux imbalance occurs if thevolt-second product across the primary while the core is set (moves in one direction along the hysteresis loop) differs from the volt-second product after it moves in the opposite direction. Thus, if the junction of C1 and C2 is not at exactly half the supply voltage, the voltage across the primary when Q1 is “on” will differ from the voltage across it when Q2 is “on” and the core will walk up or down the hysteresis loop, eventually causing saturation and destroying the transistors.This saturating effect comes about because there is an effective DC current bias in the primary. To avoid this DC bias, the blocking capacitor is placed in series in the primary. The capacitor value is selectedFIGURE 3.2 The small blocking capacitor Cb in series with the half-bridge primary (Figure 3.1) is needed to prevent flux imbalance if the junction of the filter capacitors is not at exactly the midpoint of the supply voltage. Primary current charges the capacitor, causing a droop in the primary voltage waveform. This droop should be kept to no more than 10%. (The droop in primary voltage, due to the offset charging of the blocking capacitor, is shown as dV.) as follows. The capacitor charges up as the primary current Ipft flows into it, robbing voltage from the flat-topped primary pulse shown in Figure 3.2.This DC offset robs volt-seconds from all secondary windings and forces a longer “on” time to achiev e the desired output voltage. In general, it is desirable to keep the primary voltage pulses as flat-topped as possible.In this example, we will assume a permissible droop of dV. The equivalent flat-topped current pulse that causes this droop is Ipft in Eq. 3.1. Then, because that current flows for 0.8T/2, the required capacitor magnitude is simplyCb = (3.4) Consider an example assuming a 150-W half bridge operating at 100 kHz from a nominal DC input of 320 V. At 15% low line, the DC input is 272 V and the primary voltage is ±272/2 or ±136V.A tolerable droop in the flat-topped primary voltage pulse wouldbe 10% or about 14 V.Then fromEq. 3.1 for 150Wand Vdc of 272V, Ipft =3.13×150/272= 1.73 A, and from Eq. 3.4, Cb = 1.73 ×0.8 ×5 ×10−6/14 = 0.49 F. The capacitor must be a nonpolarized type.3.2.5 Half-Bridge LeakageInductance ProblemsLeakage inductance spikes, which are so troublesome in the singleended forward converter and push-pull topology, are easily avoided in the half bridge: they are clamped to Vdc by the clamping diodes D5, D6 across transistors Q1, Q2.Assuming Q1 is “on,” the load and magnetizing currents flow through it and through the primary leakage inductance of T1, the paralleled T1 magnetizing inductance, and the secondary load impedances that are reflected by their turn ratios squared into the primary. Then it flows through Cb into the C1, C2 junction. The dot end of Np is positive with respect to its no-dot end.When Q1 turns “off,” the magnetizing indu ctance forces all winding polarities to reverse. The dot end of T1 starts to go negative by flyback action, and if this were to continue, it would put more than Vdc across Q1 and could damage it. Also, Q2 could be damaged by imposing a reverse voltage across it. However, the dot end of T1 is clamped by diode D6 to the supply rail Vdc and can go no more negative than the negative end of the supply.Similarly, when Q2 is “on,” it stores current in the magnetizinginductance, and the dot end of Np is negative with respect to the no-dot end (which is close to Vdc/2). When Q2 turns “off,” the magnetizing inductance reverses all winding polarities by flyback action and the dot end of Np tries to go positive but is caught at Vdc by clamp diode D5. Thus the energy stored in the leakage inductance during the “on” time is returned to the supply rail Vdc via diodes D5, D6.译文：第三章半桥和全桥变换器拓扑3.1 概述半桥和全桥拓扑开关管的稳态关断电压等于直流输入电压，而不像推挽、单端正激或交错正激拓扑那样为电压的两倍。

Switch mode power supply simulation with PSpice and SPICE 3第1 卷Steven M. Sandler0 篇评论McGraw-Hill Prof Med/Tech, 2006 - 235 页A master-class in power supply design through circuit simulationThis book/CD-ROM package covers every essential aspect of powersupply design simulation and fully explains the fundamentals of SPICE3 simulation techniques.•CD-ROM contains SPICE3 and ISPICE simulation models andexamples from the book, allowing easy customization SMPS simulation with SPICE 3Steven M. Sandler0 篇评论McGraw-Hill, 1997-1-1 - 187 页With the help of this time-saving book/disk package, circuit designersand engineers can successfully simulate switched mode powersupplies (SMPS) using the versatile new Spice3 software. The bookcovers all aspects of power supply design, including filters andmagnetics -- and also fully explains modeling fundamentals and Spice3simulation techniques. The accompanying disk features a wealth ofSpice3 models and examples.SPICE circuit handbookSteven M. Sandler, Charles E. Hymowitz0 篇评论McGraw-Hill Prof Med/Tech, 2006-7-11 - 310 页The expert guidance needed to customize your SPICE circuitsOver the past decade, simulation has become an increasingly integralpart of the electronic circuit design process. This resource is acompilation of 50 fully worked and simulated Spice circuits thatelectronic designers can customize for use in their own projects. Unliketraditional circuit encyclopedias Spice Circuit Handbook is unique inthat it provides designersSwitch-mode power supplies:SPICE simulations and practical designsChristophe P. Basso0 篇评论McGraw-Hill Prof Med/Tech, 2008-1-14 - 889 页Harness Powerful SPICE Simulation and Design Tools to DevelopCutting-Edge Switch-Mode Power SuppliesSwitch-Mode Power Supplies: SPICE Simulations and PracticalDesigns is a comprehensive resource on using SPICE as a powerconversion design companion. This book uniquely bridges analysis andmarket reality to teach the development and marketing of state-of-the art switching converters. Invaluable to both the graduating student and the experienced design engineer, this guide explains how to derive founding equations of the most popular converters…design safe, reliable converters through numerous practical examples…and utilize SPICE simulations to virtually breadboard a converter on the PC before using the soldering iron.Filled with more than 600 illustrations, Switch-Mode Power Supplies: SPICE Simulations and Practical Designs enables you to:•Derive founding equations of popular converters•Understand and implement loop control via the book-exclusive small-signal models •Design safe, reliable converters through practical examples•Use SPICE simulations to virtually breadboard a converter on the PC•Access design spreadsheets and simulation templates on the accompanying CD-ROM, with numerous examples running on OrCADË, ICAPSË, µCapË, TINAË, and moreInside This Powerful SPICE Simulation and Design Resource• Introduction to Power Conversion • Small-Signal Modeling • Feedback and Control Loops • Basic Blocks and Generic Models • Simulation and Design of Nonisolated Converters • Simulation and Design of Isolated Converters-Front-End Rectification and Power Factor Correction • Simulation and Design of Isolated Converters-The Flyback • Simulation and Design of Isolated Converters-The ForwardPractical computer analysis of switch mode power supplies Johnny C. BennettTaylor & Francis, 2005-7-27 - 260 页When designing switch-mode power supplies (SMPSs), engineersneed much more than simple "recipes" for analysis. Such plug-and-goinstructions are not at all helpful for simulating larger and more complexcircuits and systems. Offering more than merely a "cookbook," PracticalComputer Analysis of Switch Mode Power Supplies provides athorough understanding of the essential requirements for analyzingSMPS performance characteristics. It demonstrates the power of thecircuit averaging technique when used with powerful computer circuitsimulation programs. The book begins with SMPS fundamentals and the basics of circuit averaging models, reviewing most basic topologies and explainingSwitching power supplies A to ZSanjaya Maniktala2 篇评论Newnes, 2006-6-22 - 503 页The design of Switching Power Supplies has become one of the mostcrucial aspects of power electronics, particularly in the explosive marketfor portable devices. Unfortunately, this seemingly simple mechanism isactually one of the most complex and under-estimated processes inPower Electronics. Switching power conversion involves several engineering disciplines: Semiconductor Physics, Thermal Management, Control Loop theory, Magnetics etc, and all these come intoTroubleshooting switching power converters:a hands-on guideSanjaya Maniktala0 篇评论Newnes, 2007-8-31 - 303 页Power Supply design is all about detail. And a large part of that detaillies in the practical domain, largely because of the typically smallnumber of microseconds of switching periods involved, and the evensmaller tens of nanoseconds of switch transition times --- all these, ineffect accentuating various "second-order" effects, that eventually endup playing prime havoc with "normal" expectations of how the circuit should behave. So not unsurprisingly, even after reading several books,Switch-mode power converters:design and analysisKeng C. Wu0 篇评论Academic Press, 2006 - 392 页This book introduces an innovative, highly analytical approach tosymbolic, closed-form solutions for switched-mode power convertercircuits. This is a highly relevant topic to power electronics students andprofessionals who are involved in the design and analysis of electricalpower converters. The author uses extensive equations to explain howsolid-state switches convert electrical voltages from one level toanother, so that electronic devices (e.g., audio speakers, CD players,Complex behavior of switching power convertersChi Kong Tse0 篇评论CRC Press, 2004 - 262 页Power electronics is a discipline spawned by real-life applications andevolving from the need to solve power conversion problems. Historically,system implementations or circuit topologies found widespreadapplication long before they were thoroughly analyzed. Today, however,engineers must thoroughly understand the nonlinear behavior of asystem to achieve the better design, functionality, and reliability thatmodern applications plex Behavior of Switching Power Converters provides a systematic treatment of the procedures for observing, identifying, and diagnosing switching converter phenomena such as chaos and bifurcation. After a review of the fundamentals, the author presents some recent findings and discusses computer, laboratory, and modeling techniques for studying complex behaviors. The focus then moves to the nonlinear dynamics of various switching coverters. Here the author emphasizes circuit operation rather than mathematical abstraction, and whenever possibe, explains phenomena in terms of the physical circuit operation.Knowing when and how nonlinear phenomena occur is essential in the design and operation of power electronics. With a careful balance of theory, computer techniques, and laboratory experiments, this treatment forms a practical reference for engineers and an ideal starting point for anyone who needs a basic understanding of analyzing complex behavior in power converters.Power-switching converters:medium and high powerDorin O. Neacsu0 篇评论CRC/Taylor & Francis, 2006-5-25 - 365 页Power converters are at the heart of modern power electronics. Fromautomotive power systems to propulsion for large ships, their usepermeates through industrial, commercial, military, and aerospaceapplications of various scales. Having reached a point of saturationwhere we are unlikely to see many new and revolutionary technologies,industry now seeks to optimize and standardize the performance ofthese devices. Power-Switching Converters: Medium and High Power examines the characteristics and operating principles of these systems in terms of how to increase their efficiency and produce them at lower cost.This book begins with an introduction to the field, placing the technology in its business context to highlight the current trends and issues facing the modern power engineer. The remainder of the book provides a detailed examination of three-phase power switching converters, including the various problems and solutions involved in different applications. It discusses high-power semiconductor devices, pulse-width modulation (PWM) principles and algorithms for various implementations,closed-loop current control, component-minimized topologies, power grid interface, parallel and interleaved power converters, and practical aspects such as protection and thermal management.Filling the gap between textbooks and technical papers, Power-Switching Converters: Medium and High Power offers practical solutions to current industrial demands with a focus on the particular business needs of performance quality and cost efficiency. It alsoPower-switching convertersSimon S. Ang, Alejandro Oliva1 评论Taylor & Francis, 2005-3-17 - 540 页After nearly a decade of success owing to its thorough coverage,abundance of problems and examples, and practical use of simulationand design, Power-Switching Converters enters its second edition withnew and updated material, entirely new design case studies, andexpanded figures, equations, and homework problems. This textbook isideal for senior undergraduate or graduate courses in power electronicconverters, requiring only systems analysis and basic electronics Power supply cookbookMarty Brown0 篇评论Newnes, 2001-5-3 - 280 页Power Supply Cookbook, Second Edition provides an easy-to-follow,step-by-step design framework for a wide variety of power supplies.With this book, anyone with a basic knowledge of electronics can createa very complicated power supply design in less than one day. With thecommon industry design approaches presented in each section, thisunique book allows the reader to design linear, switching, andquasi-resonant switching power supplies in an organized fashion. Formerly complicated design topics such as magnetics, feedback loop compensation design, and EMI/RFI control are all described in simple language and design steps. This book also details easy-to-modify design examples that provide the reader with a design template useful for creating a variety of power supplies.Power supplies, switching regulators, inverters, and convertersIrving M. Gottlieb1 评论McGraw-Hill Professional, 1994 - 479 页An all-in-one guide to design, applications, and operation--withhundreds of helpful schematics and diagrams. Updated to cover new ICtechnology, low-voltage logic devices, and one-watt power supplies forISDN equipment. Detailed enough for professional engineers andtechnicians . . . accessible enough for students and hobbyists.Simplified design of switching power suppliesJohn D. Lenk0 篇评论Elsevier, 1995 - 224 页An all-inclusive, one-step guide to switching power-supply design, thisunique book describes the operation of each circuit in detail, requiringno previous design experience to use the techniques. Step-by-stepinstructions and diagrams render this book essential for the student, theexperimenter, and the design professional.Dc Power Supplies: A Technician's GuideJoseph J. Carr0 篇评论TAB Books, 1996-7-1 - 326 页Design any internal or external DC power supply. Sharpen yourtechnical mastery of dc power supplies and keep your electronicscareer on the fast track with DC Power Supplies, by Joseph J. Carr. It'syour complete, on-to-the-job guide to building virtually every kind ofinternal and external dc power supply - high-voltage, remote, portable and emergency. You'll hone your skills with build-it-yourself projects and work with real-world components and values to: Design and buildBuilding power suppliesDavid Lines0 篇评论Master Pub., 1997-6-1 - 124 页Power supplies, the basic sources of energy in all electronic equipment,are essential to electronic design and construction. Power Supplies:Projects for the Hobbyist and Technician guides you from thefundamentals of power supply components and their functions to thedesign and construction of a power supply system.The comprehensive coverage includes:Introduction to power electronicsDaniel W. Hart1 评论Prentice Hall, 1997 - 418 页This book is intended to be an introductory text in power electronics,primarily for the undergraduate electrical engineering student. The textassumes that the student is familiar with general circuit analysistechniques usually taught at the sophomore level. The student shouldbe acquainted with electronic devices such as diodes and transistors,Introduction to power electronicsDenis Fewson0 篇评论Butterworth-Heinemann, 1998-3-27 - 208 页Building on solid state device and electromagnetic contributions to theseries, this text book introduces modern power electronics, that is theapplication of semiconductor devices to the control and conversion ofelectrical power. The increased availability of solid state power switcheshas created a very rapid expansion in applications, from the relativelylow power control of domestic equipment, to high power control of industrial processes and very high power control alongDemystifying switching power suppliesRaymond A. Mack0 篇评论Newnes, 2005-4-5 - 323 页This book is a crash course in the fundamental theory, concepts, andterminology of switching power supplies. It is designed to quicklyprepare engineers to make key decisions about power supplies for theirprojects. Intended for readers who need to quickly understand the keypoints of switching power supplies, this book covers the 20% of the topic that engineers use, 80% of the time. Unlike existing switching power supply books that deal strictly with design issues, this book also recognizes the growing importance of"off-the-shelf" commercial switching power supplies, giving readers the background necessary to select the right commercial supply. This book covers the core essentials of power supply theory and design while keeping mathematics to the absolute minimum necessary. CMOS Integrated Switching Power Converters:A Structured Design ApproachSpringer, 2011-5-30 - 313 页This book describes the structured design and optimization of efficient,energy processing integrated circuits. The approach is multidisciplinary,covering the monolithic integration of IC design techniques, powerelectronics and control theory. In particular, this book enables readersto conceive, synthesize, design and implement integrated circuits withhigh-density high-efficiency on-chip switching power regulators. Topicscovered encompass the structured design of the on-chip power supply,efficiency optimization, IC-compatible power inductors and capacitors,power MOSFET switches and efficient switch drivers in standardCMOS technologies. Provides a comprehensive reference on structured design and optimization of fully monolithic power supplies for on-chip power management; Describes a multidisciplinary approach, encompassing enhanced integrated power devices, both active and reactive, as well as advanced circuit topologies and switching control methods, together with their implementation; Enables concurrent design of compact adaptive power supplies, together with system-level and circuit-level techniques. .Practical switching power supply designMarty Brown0 篇评论Academic Press, 1990 - 240 页Take the "black magic" out of switching power supplies with PracticalSwitching Power Supply Design! This is a comprehensive"hands-on" guide to the theory behind, and design of, PWM andresonant switching supplies. You'll find information on switching supplyoperation and selecting an appropriate topology for your application.There's extensive coverage of buck, boost, flyback, push-pull, half bridge, and full bridge regulator circuits. Special attention is given toPower sources and supplies: world class designsMarty Brown0 篇评论Newnes, 2007-12-7 - 381 页Newnes has worked with Marty Brown, a leader in the field of powerdesign to select the very best design-specific material from the Newnesportfolio. Marty selected material for its timelessness, its relevance tocurrent power supply design needs, and its real-world approach todesign issues. Special attention is given to switching power supplies and their design issues, including component selection, minimization of EMI, toroid selection, and breadboarding of designs. Emphasis is also placed on design strategies for power supplies, including case histories and design examples. This is a book that belongs on the workbench of every power supply designer! *Marty Brown, author and power supply design consultant, has personally selected all content for its relevance and usefulness *Covers best design practices for switching power supplies and power converters *Emphasis is on pragmatic solutions to commonly encountered design problems and tasksPower supplies for LED drivingSteve WinderNewnes, 2008-3-18 - 232 页Light-emitting diodes are being widely used due to their efficient use ofpower. The applications for power LEDs include traffic lights, streetlamps, automotive lighting, architectural lights, household lightreplacements, signage lighting (replacing neon strip lights andfluorescent tubes), and many more. Powering (driving) these LED's isnot always simple. Linear driving is inefficient and generates far toomuch heat. With a switching supply, the main issues are EMI andefficiency, and of course cost. The problem is to get a design that meets legal requirements and is efficient, while costing the least. This book covers the designtrade-offs involved in LED driving applications, from low-power to UB-LEDs and beyond. * Practical, "hands-on" approach to power supply design for LED drivers; * Detailed examples of what works and why, throughout the design process; * Commentary on how the calculated component value compares with the actual value used, including a description of why theMcGraw-Hill circuit encyclopedia and troubleshooting guide, 第3 卷John D. Lenk0 篇评论McGraw-Hill Professional, 1996-5-1 - 706 页This volume includes over 700 new circuits commonly used in allphases of electronics. In addition to details on component values, thereare descriptions on how the circuits operate and where they fit intoelectronic systems. Included is a practical guide.Winn L. Rosch hardware bibleQue Publishing, 2003 - 1128 页The Winn L. Rosch Hardware Bible provides a background on howthings work, puts competing technologies, standards, and products inperspective, and serves as a reference that provides quick answers forcommon computer and technology questions. It functions as a buyingguide, telling not only what to buy, but why. It also lays the foundationfor upgrading or repairing a computer, but stops short of thestep-by-step mechanics of the process. The chief purpose of theHardware Bible remains educational. Some new features in this edition include rewritable DVD technology as well as Blu-ray DiscsEMC for product designersNewnes, 2007-3-28 - 498 页Widely regarded as the standard text on EMC, Tim Williams' bookprovides all the key information needed to meet the requirements of thelatest EMC Directive. Most importantly, it shows how to incorporateEMC principles into the product design process, avoiding cost andperformance penalties, meeting the needs of specific standards andresulting in a better overall product. As well as covering the very latestlegal requirements, the fourth edition has been thoroughly updated inline with the latest best practice in EMC compliance and product design.Coverage has been considerably expanded to include the R&TTE andAutomotive EMC Directives, as well the military aerospace standards of DEF STAN 59-41 and DO160E. A new chapter on systems EMC is included, while short case studies demonstrate how EMC product design is put into practice. Tim Williams has worked for a variety of companies as an electronic design engineer over the last 25 years. He has monitored the progress of the EMC Directive and its associated standards since it was first made public. He now runs his own consultancy specialising in EMC design and test advice and training. * Includes the compliance procedures of the latest EMC Directive: 2004/108/EC * Short case studies demonstrating how EMC product design is put into practice. * Packed full with many new chapters including: - The R&TTE Directive and the Automotive EMC Directive looking at compliance aspects of radio and telecom terminal equipment and automotive electronic products - New chapter on military aerospace standards of DEP STAN 59-41 and DO1 60E - New chapter on systems EMC。

中文4060字外文文献Switched-mode power supplyA switched-mode power supply (also switching-mode power supply, SMPS, or simply switcher) is an electronic power supply unit (PSU) that incorporates a switching regulator. While a linear regulator maintains the desired output voltage by dissipating excess power in a pass power transistor, the switched-mode power supply switches a power transistor between saturation (full on) and cutoff (completely off) with a variable duty cycle whose average is the desired output voltage. It switches at a much-higher frequency (tens to hundreds of kHz) than that of the AC line (mains), which means that the transformer that it feeds can be much smaller than one connected directly to the line/mains. Switching creates a rectangular waveform that typically goes to the primary of the transformer; typically several secondaries feed rectifiers, series inductors, and filter capacitors to provide various DC outputs with low ripple.The main advantage of this method is greater efficiency because the switching transistor dissipates little power in the saturated state and the off state compared to the semiconducting state (active region). Other advantages include smaller size and lighter weight (from the elimination of low frequency transformers which have a high weight) and lower heat generation due to higher efficiency. Disadvantages include greater complexity, the generation of high amplitude, high frequency energy that the low-pass filter must block to avoid electromagnetic interference (EMI), and a ripple voltage at the switching frequency and the harmonic frequencies thereof.A note about terminologyAlthough the term "power supply" has been in use since radios were first powered from the line/mains, that does not mean that it is a source of power, in the sense that a battery provides power. It is simply a device that (usually) accepts commercial AC power and provides one or more DC outputs. It would be more correctly referred to as a power converter, but long usage has established the term. ClassificationSMPS can be classified into four types according to the input and output waveforms: AC in, DC out: rectifier, off-line converter input stageDC in, DC out: voltage converter, or current converter, or DC to DC converterAC in, AC out: frequency changer, cycloconverter, transformerDC in, AC out: inverterInput rectifier stageIf the SMPS has an AC input, then the first stage is to convert the input to DC. This is called rectification. The rectifier circuit can be configured as a voltage doubler by the addition of a switch operated either manually or automatically. This is a feature of larger supplies to permit operation from nominally 120 volt or 240 volt supplies. The rectifier produces an unregulated DC voltage which is then sent to a large filter capacitor. The current drawn from the mains supply by this rectifier circuit occurs in short pulses around the AC voltage peaks. These pulses have significant high frequency energy which reduces the power factor. Special control techniques can be employed by the following SMPS to force the average input current to follow the sinusoidal shape of the AC input voltage thus the designer should try correcting the power factor. An SMPS with a DC input does not require this stage. An SMPS designed for AC input can often be run from a DC supply (for 230V AC this would be 330V DC), as the DC passes through the rectifier stage unchanged. It's however advisable to consult the manual before trying this, though most supplies are quite capable of such operation even though nothing is mentioned in the documentation. However, this type of use may be harmful to the rectifier stage as it will only utilize half of diodes in the rectifier for the full load. This may result in overheating of these components, and cause them to fail prematurely.If an input range switch is used, the rectifier stage is usually configured to operate as a voltage doubler when operating on the low voltage (~120 V AC) range and as a straight rectifier when operating on the high voltage (~240 V AC) range. If an input range switch is not used, then a full-wave rectifier is usually used and the downstream inverter stage is simply designed to be flexible enough to accept the wide range of dc voltages that will be produced by the rectifier stage. In higher-power SMPSs, some form of automatic range switching may be used.Inverter stageThe inverter stage converts DC, whether directly from the input or from the rectifier stage described above, to AC by running it through a power oscillator, whoseoutput transformer is very small with few windings at a frequency of tens or hundreds of kilohertz (kHz). The frequency is usually chosen to be above 20 kHz, to make it inaudible to humans. The output voltage is optically coupled to the input and thus very tightly controlled. The switching is implemented as a multistage (to achieve high gain) MOSFET amplifier. MOSFETs are a type of transistor with a low on-resistance and a high current-handling capacity. Since only the last stage has a large duty cycle, previous stages can be implemented by bipolar transistors leading to roughly the same efficiency. The second last stage needs to be of a complementary design, where one transistor charges the last MOSFET and another one discharges the MOSFET. A design using a resistor would run idle most of the time and reduce efficiency. All earlier stages do not weight into efficiency because power decreases by a factor of 10 for every stage (going backwards) and thus the earlier stages are responsible for at most 1% of the efficiency. This section refers to the block marked Chopper in the block diagram.V oltage converter and output rectifierIf the output is required to be isolated from the input, as is usually the case in mains power supplies, the inverted AC is used to drive the primary winding of a high-frequency transformer. This converts the voltage up or down to the required output level on its secondary winding. The output transformer in the block diagram serves this purpose.If a DC output is required, the AC output from the transformer is rectified. For output voltages above ten volts or so, ordinary silicon diodes are commonly used. For lower voltages, Schottky diodes are commonly used as the rectifier elements; they have the advantages of faster recovery times than silicon diodes (allowing low-loss operation at higher frequencies) and a lower voltage drop when conducting. For even lower output voltages, MOSFETs may be used as synchronous rectifiers; compared to Schottky diodes, these have even lower conducting state voltage drops.The rectified output is then smoothed by a filter consisting of inductors and capacitors. For higher switching frequencies, components with lower capacitance and inductance are needed.Simpler, non-isolated power supplies contain an inductor instead of a transformer. This type includes boost converters, buck converters, and the so called buck-boost converters. These belong to the simplest class of single input, single output converters which utilize one inductor and one active switch. The buck converter reduces the input voltage in direct proportion to the ratio of conductive time to the total switchingperiod, called the duty cycle. For example an ideal buck converter with a 10 V input operating at a 50% duty cycle will produce an average output voltage of 5 V. A feedback control loop is employed to regulate the output voltage by varying the duty cycle to compensate for variations in input voltage. The output voltage of a boost converter is always greater than the input voltage and the buck-boost output voltage is inverted but can be greater than, equal to, or less than the magnitude of its input voltage. There are many variations and extensions to this class of converters but these three form the basis of almost all isolated and non-isolated DC to DC converters. By adding a second inductor the Ćuk and SEPIC converters can be implemented, or, by adding additional active switches, various bridge converters can be realised.Other types of SMPSs use a capacitor-diode voltage multiplier instead of inductors and transformers. These are mostly used for generating high voltages at low currents (Cockcroft-Walton generator). The low voltage variant is called charge pump. RegulationA feedback circuit monitors the output voltage and compares it with a reference voltage, which is set manually or electronically to the desired output. If there is an error in the output voltage, the feedback circuit compensates by adjusting the timing with which the MOSFETs are switched on and off. This part of the power supply is called the switching regulator. The Chopper controller shown in the block diagram serves this purpose. Depending on design/safety requirements, the controller may or may not contain an isolation mechanism (such as opto-couplers) to isolate it from the DC output. Switching supplies in computers, TVs and VCRs have these opto-couplers to tightly control the output voltage.Open-loop regulators do not have a feedback circuit. Instead, they rely on feeding a constant voltage to the input of the transformer or inductor, and assume that the output will be correct. Regulated designs compensate for the parasitic capacitance of the transformer or coil. Monopolar designs also compensate for the magnetic hysteresis of the core.The feedback circuit needs power to run before it can generate power, so an additional non-switching power-supply for stand-by is added.Transformer designSMPS transformers run at high frequency. Most of the cost savings (and space savings) in off-line power supplies come from the fact that a high frequency transformer is much smaller than the 50/60 Hz transformers formerly used.There are several differences in the design of transformers for 50 Hz vs 500 kHz. Firstly a low frequency transformer usually transfers energy through its core (soft iron), while the (usually ferrite) core of a high frequency transformer limits leakage. Since the waveforms in a SMPS are generally high speed (PWM square waves), the wiring must be capable of supporting high harmonics of the base frequency due to the skin effect, which is a major source of power loss.Power factorSimple off-line switched mode power supplies incorporate a simple full wave rectifier connected to a large energy storing capacitor. Such SMPSs draw current from the AC line in short pulses when the mains instantaneous voltage exceeds the voltage across this capacitor. During the remaining portion of the AC cycle the capacitor provides energy to the power supply.As a result, the input current of such basic switched mode power supplies has high harmonic content and relatively low power factor. This creates extra load on utility lines, increases heating of the utility transformers and standard AC electric motors, and may cause stability problems in some applications such as in emergency generator systems or aircraft generators. Harmonics can be removed through the use of filter banks but the filtering is expensive, and the power utility may require a business with a very low power factor to purchase and install the filtering onsite.In 2001 the European Union put into effect the standard IEC/EN61000-3-2 to set limits on the harmonics of the AC input current up to the 40th harmonic for equipment above 75 W. The standard defines four classes of equipment depending on its type and current waveform. The most rigorous limits (class D) are established for personal computers, computer monitors, and TV receivers. In order to comply with these requirements modern switched-mode power supplies normally include an additional power factor correction (PFC) stage.Putting a current regulated boost chopper stage after the off-line rectifier (to charge the storage capacitor) can help correct the power factor, but increases the complexity (and cost).Quasiresonant ZCS/ZVSA quasiresonant ZCS/ZVS switch (Zero Current/Zero Voltage) is a design where "each switch cycle delivers a quantized 'packet' of energy to the converter output, and switch turn-on and turn-off occurs at zero current and voltage, resulting in an essentially lossless switch."EfficiencyHigher input voltage and synchronous rectification mode makes the conversion process more efficient. Higher switch frequency allows component size to be shrunk, but suffer from radio frequency (RF) properties on the other hand. The power consumption of the controller also has to be taken into account.ApplicationsSwitched-mode PSUs in domestic products such as personal computers often have universal inputs, meaning that they can accept power from most mains supplies throughout the world, with rated frequencies from 50 Hz to 60 Hz and voltages from 100 V to 240 V (although a manual voltage range switch may be required). In practice they will operate from a much wider frequency range and often from a DC supply as well. In 2006, at an Intel Developers Forum, Google engineers proposed the use of a single 12 V supply inside PCs, due to the high efficiency of switch mode supplies directly on the PCB.Most modern desktop and laptop computers already have a DC-DC converter on the motherboard, to step down the voltage from the PSU or the battery to the CPU core voltage, as low as 0.8 V for a low voltage CPU to 1.2-1.5 V for a desktop CPU as of 2007. Most laptop computers also have a DC-AC inverter to step up the voltage from the battery to drive the backlight, typically around 1000 Vrms.Certain applications, such as in automobile industry where ordinary cars often use 12 V DC and in some industrial settings, DC supply is chosen to avoid hum and interference and ease the integration of capacitors and batteries used to buffer the voltage. Most small aircraft use 28 V DC, but larger aircraft like Boeing-747 often use up to 90 kV A 3-phase at 200 V AC 400 Hz, though they often have a DC bus as well. Even fighter planes like F-16 use 400 Hz power. The MD-81 airplane has an 115/200 V 400 Hz AC and 28 V DC power system generated by three 40 kV A AC generators. Helicopters also use the 28 V DC system. Some submarines like the Soviet Alfa class submarine utilized two synchronous generators providing a variable three-phase current, 2 x 1500 kW, 400 V, 400 Hz. The space shuttle uses three fuel cells generating 30 - 36 V DC. Some is converted into 400 Hz AC power and 28 V DC power. The International Space Station uses 120 V DC power. Larger trucks uses 24 V DC.See also: Avionics, Airplane ground supportIn the case of TV sets, for example, one can test the excellent regulation of thepower supply by using a variac. For example, in some models made by Philips, the power supply starts when the voltage reaches around 90 volts. From there, one can change the voltage with the variac, and go as low as 40 volts and as high as 260 (known such case that voltage was 360), and the image will show absolutely no alterations.TerminologyThe term switchmode was widely used until Motorola trademarked SWITCHMODE(TM), for products aimed at the switching-mode power supply market, and started to enforce their trademark.外文翻译开关模式电源开关模式电源（也开关式电源，开关电源，或只是交换机）是一种电子电源供应器（电源），包含了开关稳压器。

Intelligent switch power supply英文：With the rapid development of electronic technology, application field of electronic system is more and more extensive, electronic equipment, there are more and more people work with electronic equipment, life is increasingly close relationship. Any electronic equipment are inseparable from reliable power supply for power requirements, they more and more is also high. Electronic equipment miniaturized and low cost in the power of light and thin, small and efficient for development direction. The traditional transistors series adjustment manostat is continuous control linear manostat. This traditional manostat technology more mature, and there has been a large number of integrated linear manostat module, has the stable performance is good, output ripple voltage small, reliable operation, etc. But usually need are bulky and heavy industrial frequency transformer and bulk and weight are big filter.In the 1950s, NASA to miniaturization, light weight as the goal, for a rocket carrying the switch power development. In almost half a century of development process, switch power because of its small volume, light weight, high efficiency, wide range, voltage advantages in electric, control, computer, and many other areas of electronic equipment has been widely used. In the 1980s, a computer is made up of all of switch power supply, the first complete computer power generation. Throughout the 1990s, switching power supply in electronics, electrical equipment, home appliances areas to be widely, switch power technology into the rapid development. In addition, large scale integrated circuit technology, and the rapid development of switch power supply with a qualitative leap, raised high frequency power products of, miniaturization, modular tide.Power switch tube, PWM controller and high-frequency transformer is an indispensable part of the switch power supply. The traditional switch power supply is normally made by using high frequency power switch tube division and the pins, such as using PWM integrated controller UC3842 + MOSFET is domestic small powerswitch power supply, the design method of a more popularity.Since the 1970s, emerged in many function complete integrated control circuit, switch power supply circuit increasingly simplified, working frequency enhances unceasingly, improving efficiency, and for power miniaturization provides the broad prospect. Three end off-line pulse width modulation monolithic integrated circuit TOP (Three switch Line) will Terminal Off with power switch MOSFET PWM controller one package together, has become the mainstream of switch power IC development. Adopt TOP switch IC design switch power, can make the circuit simplified, volume further narrowing, cost also is decreased obviouslyMonolithic switching power supply has the monolithic integrated, the minimalist peripheral circuit, best performance index, no work frequency transformer can constitute a significant advantage switching power supply, etc. American PI (with) company in Power in the mid 1990s first launched the new high frequency switching Power supply chip, known as the "top switch Power", with low cost, simple circuit, higher efficiency. The first generation of products launched in 1994 represented TOP100/200 series, the second generation product is the TOP Switch - debuted in 1997 Ⅱ. The above products once appeared showed strong vitality and he greatly simplifies thedesign of 150W following switching power supply and the development of new products for the new job, also, high efficiency and low cost switch power supply promotion and popularization created good condition, which can be widely used in instrumentation, notebook computers, mobile phones, TV, VCD and DVD, perturbation VCR, mobile phone battery chargers, power amplifier and other fields, and form various miniaturization, density, on price can compete with the linear manostat AC/DC power transformation module.Switching power supply to integrated direction of future development will be the main trend, power density will more and more big, to process requirements will increasingly high. In semiconductor devices and magnetic materials, no new breakthrough technology progress before major might find it hard to achieve, technology innovation will focus on how to improve the efficiency and focus onreducing weight. Therefore, craft level will be in the position of power supply manufacturing higher in. In addition, the application of digital control IC is the future direction of the development of a switch power. This trust in DSP for speed and anti-interference technology unceasing enhancement. As for advanced control method, now the individual feels haven't seen practicability of the method appears particularly strong,perhaps with the popularity of digital control, and there are some new control theory into switching power supply.（1）The technology: with high frequency switching frequencies increase, switch converter volume also decrease, power density has also been boosted, dynamic response improved. Small power DC - DC converter switch frequency will rise to MHz. But as the switch frequency unceasing enhancement, switch components and passive components loss increases, high-frequency parasitic parameters and high-frequency EMI and so on the new issues will also be caused.（2）Soft switching technologies: in order to improve the efficiency of non-linearity of various soft switch, commutation technical application and hygiene, representative of soft switch technology is passive and active soft switch technology, mainly including zero voltage switch/zero current switch (ZVS/ZCS) resonance, quasi resonant, zero voltage/zero current pulse width modulation technology (ZVS/ZCS - PWM) and zero voltage transition/zero current transition pulse width modulation (PWM) ZVT/ZCT - technical, etc. By means of soft switch technology can effectively reduce switch loss and switch stress, help converter transformation efficiency （3）Power factor correction technology (IC simplifies PFC). At present mainly divided into IC simplifies PFC technology passive and active IC simplifies PFC technology using IC simplifies PFC technology two kinds big, IC simplifies PFC technology can improve AC - DC change device input power factor, reduce the harmonic pollution of power grid.（4）Modular technology. Modular technology can meet the needs of the distributed power system, enhance the system reliability.（5）Low output voltage technology. With the continuous development of semiconductor manufacturing technology, microprocessor and portable electronic devices work more and more low, this requires future DC - DC converter can provide low output voltage to adapt microprocessor and power supply requirement of portable electronic devicesPeople in switching power supply technical fields are edge developing related power electronics device, the side of frequency conversion technology, development of switch between mutual promotion push switch power supply with more than two year growth toward light, digital small, thin, low noise and high reliability, anti-interference direction. Switching powersupply can be divided into the AC/DC and DC/DC two kinds big, also have AC/AC DC/AC as inverter DC/DC converter is now realize modular, and design technology and production process at home and abroad, are mature and standardization, and has approved by users, but the AC/DC modular, because of its own characteristics in the process of making modular, meet more complex technology and craft manufacture problems. The following two types of switch power supply respectively on the structure and properties of this.Switching power supply is the development direction of high frequency, high reliability, low consumption, low noise, anti-jamming and modular. Because light switch power, small, thin key techniques are changed, so high overseas each big switch power supply manufacturer are devoted to the development of new high intelligent synchronous rectifier, especially the improvement of secondary devices of the device, and power loss of Zn ferrite (Mn) material? By increasing scientific and technological innovation, to enhance in high frequency and larger magnetic flux density (Bs) can get high magnetic under the miniaturization of, and capacitor is a key technology. SMT technology application makes switching power supply has made considerable progress, both sides in the circuitboard to ensure that decorate components of switch power supply light, small, thin. The high frequency switching power supply of the traditional PWM must innovate switch technology, to realize the ZCS ZVS, soft switch technology hasbecome the mainstream of switch power supply technical, and greatly improve the efficiency of switch power. For high reliability index, America's switch power producers, reduce by lowering operating current measures such as junction temperature of the device, in order to reduce stress the reliability of products made greatly increased.Modularity is of the general development of switch power supply trend can be modular power component distributed power system, can be designed to N + 1 redundant system, and realize the capacity expansion parallel. According to switch power running large noise this one defect, if separate the pursuit of high frequency noise will increase its with the partial resonance, and transform circuit technology, high frequency can be realized in theory and can reduce the noise, but part of the practical application of resonant conversion technology still have a technical problem, so in this area still need to carry out a lot of work, in order to make the technology to practional utilization.Power electronic technology unceasing innovation, switch power supply industry has broad prospects for development. To speed up the development of switch power industry in China, we must walk speed of technological innovation road, combination with Chinese characteristics in the joint development path, for I the high-speed development of national economy to make the contribution. The basic principle and component functionAccording to the control principle of switch power to classification, we have the following 3 kinds of work mode:1) pulse width adjustment type, abbreviation Modulation Pulse Width pulse width Modulation (PWM) type, abbreviation for. Its main characteristic is fixed switching frequency, pulse width to adjust by changing voltage 390v, realize the purpose. Its core is the pulse width modulator. Switch cycle for designing filter circuit fixed provided convenience. However, its shortcomings is influenced by the power switch conduction time limit minimum of output voltage cannot be wide range regulation; In addition, the output will take dummy loads commonly (also called pre load), in order to prevent the drag elevated when output voltage. At present, most ofthe integrated switch power adopt PWM way.2) pulse frequency Modulation mode pulse frequency Modulation (, referred to Pulse Frequency Modulation, abbreviation for PFM) type. Its characteristic is will pulse width fixed by changing switch frequency to adjust voltage 390v, realize the purpose. Its core is the pulse frequency modulator. Circuit design to use fixed pulse-width generator to replace the pulse width omdulatros and use sawtooth wave generator voltage？Frequency converter (for example VCO changes frequency VCO). It on voltage stability principle is: when the output voltage Uo rises, the output signal controller pulse width unchanged and cycle longer, make Uo 390v decreases, and reduction. PFM type of switch power supply output voltage range is very wide, output terminal don't meet dummy loads. PWM way and way of PFM respectively modulating waveform is shown in figure 1 (a), (b) shows, tp says pulse width (namely power switch tube conduction time tON), T represent cycle. It can be easy to see the difference between the two. But they have something in common: (1) all use time ratio control (TRC) on voltage stability principle, whether change tp, finally adjustment or T is pulse 390v. Although adopted in different ways, but control goals, is all rivers run into the sea. (2) when load by light weight, or input voltage respectively, from high changed by increasing the pulse width, higher frequency method to make the output voltage remained stable.3) mix modulation mode, it is to point to the pulse width and switching frequency is not fixed, each other can change, it belongs to the way the PWM and PFM blend mode. It contains a pulsewidthomdulatros and pulse frequency modulator. Because and T all can adjust alone, so occupies emptiescompared to adjust the most wide range, suitable for making the output voltage for laboratories that use a wide range of can adjust switching power supply. Above 3 work collectively referred to as "Time Ratio Control" (as a Control, from TRC) way. As noted, pulse width omdulatros either as a independent IC use (for example UC3842 type pulse width omdulatros), can also be integrated in DC/DC converter (for example LM2576 type switching voltage regulators integrated circuit), still can integration in AC/DC converter (for exampleTOP250 type monolithic integrated circuit switching power supply. Among them, the switching voltage regulators belong to DC/DC power converter, switching power supply general for AC/DC power converter.The typical structure of switch power as figure1shows, its working principle is: the first utility into power rectifier and filtering into high voltage dc and then through the switch circuit and high-frequency switch to high frequency low pressure pulse transformer, and then after rectification and filter circuits, finally output low voltage dc power. Meanwhile in the output parts have a circuit feedback to control circuit, through the control PWM occupies emptiescompared to achieve output voltage stability.Figure 1 typical structure of switch power supplySwitching power supply by these four components:1) the main circuit: exchange network input, from the main circuit to dc output. Mainly includes input filter, rectifier and filtering, inverter, and output rectifier and filtering.(1) input filter: its effect is the power grid existing clutter filtering, also hinder the machine produces clutter feedback to public power grid.(2) rectifier and filter: the power grid ac power directly for a smooth dc rectifier, for the next level transformation.(3) inverter: will the dc after rectifying a high-frequency ac, this is the core of high frequency switching power supply, the higher the frequency, the volume, weight and the ratio of power output and smaller.(4) Out put rectifier and filter: according to load needs, providing stable and reliable dc power supply. 2) control circuit: on the one hand, from the output bysampling with set standards to compare, and then to control inverter, changing its frequency or pulse width, achieve output stability, on the other hand, according to data provided by the test circuit, the protection circuit differential, provide control circuit to the machine to various protection measures. Including the output feedback circuit and sampling circuit, pulse width modulator. 3) the detection and protection circuit: detection circuit had current detection, over-voltage detection, owe voltage detection, overheat detection, etc.; Protection circuit can be divided over current protection, over-voltage protection, owe voltage protection, the ground-clamp protection, overheating protection, automatic restart, soft start, slow startup, etc. Various types. 4) Other circuit: if the sawtooth wave generator, offset circuit, optical coupler, etc.智能开关电源中文：随着电子技术的高速发展，电子系统的应用领域越来越广泛，电子设备的种类也越来越多，电子设备与人们的工作、生活的关系日益密切。

外文资料译文THE DEVELOPMENT OF SWITCHING POWER 1955 United States Royer (GH.Roger) invented the transistor single push-pull oscillation transformer DC-DC converter, frequency conversion control circuit to achieve the beginning of 1957, the United States Charles race (Jen Sen) invented the self-excited push-pull double transformer, in 1964 U.S. scientists have proposed to abolish the frequency transformer switching power supply series idea, which is the power to decline in volume and weight were a fundamental way. To 1969 because of pressure to improve high-power silicon transistors, diode reverse recovery time shortened components to improve, and finally made a 25 kHz switching power supply. At present, switching power supply to small, light weight and high efficiency characteristics are widely used in a variety of computer-driven devices, communications equipment, etc. Almost all the electronic equipment is the rapid development of today's electronic information industry, an indispensable Power Source. Currently on the market the use of switching power bipolar transistors made of 100kHz, 500kHz with a power MOSFET made, Although practical, its frequency needs to be improved. To improve the switching frequency, it is necessary to reduce switching losses, and to reduce switching losses, it needs high-speed switching components. However, the switching speed of the increase will be distributed by the circuit inductance and capacitance, or diode stored charge of the generated surge or noise. This will not only affect nearby electronic equipment, will greatly reduce the reliability of power supply itself. Which, with the switch to prevent Kai - closed by the voltage surge occurs, can use RC or LC buffer, while the stored charge from the diode can be used due to current surges such as core made of amorphous magnetic buffer .However, for more than 1MHz frequency, resonant circuit to be used to make the switch voltage or current through the switch was a sine wave, this can reduce the switching losses, but also to control the occurrence of surge. This switch is called resonant switch. Current switching power supply of this very active, because this approach does not require substantial increase in switching speed can be reduced theoretically to zero switching losses and noise are small, is expected to be of a high-frequency switching power supply main ways. At present, many countries are working on a few trillion Hz, the practical application of converter.Switching power supply direction of development is high-frequency, high reliability, low power, low noise, interference and modular. Oxygen material increase scientific and technological innovation to enhance the high frequency and higher magnetic flux density (Bs) obtained a high magnetic properties, while the small capacitor is a key technology. SMT technology allows switching power supply hasmade considerable progress, both sides of the circuit board layout components to ensure that the switching power supply of light, small, thin. High frequency switching power supply will be bound to the traditional PWM switching technology innovation, realization of ZVS, ZCS soft switching power supply switching technology has become the mainstream technology, and a substantial increase in the switching power supply efficiency.For high reliability, the U.S. manufacturer of switching power supply by reducing operating current to reduce junction temperature and other measures to reduce the stress of the device makes the improved reliability of products.Modular switching power supply is the general trend of development can be composed of modular power distributed power systems can be designed to N +1 redundant power systems, and parallel way to achieve the capacity expansion. Switching power supply noise for the big run this shortcoming, if the individual pursuit of its high-frequency noise will also increase with, while using some of the resonant converter circuit technology, in theory, but also can reduce the high frequency of the noise, but some the practical application of resonant conversion technology, there are still technical problems, it still required much work in this area in order to make the technology to practical use.With the power electronics technology development, switching power supply industry has a bright future. Switching power supply industry in China should speed up the pace of development, we must take the technical innovation, out of the Industry and Academia with Chinese characteristics development road, as the rapid development of our national economy to contribute.开关电源的发展1955年美国罗耶（GH.Roger)发明的自激振荡推挽晶体管单变压器直流变换器，是实现高频转换控制电路的开端，1957年美国查赛（Jen Sen)发明了自激式推挽双变压器，1964年美国科学家们提出取消工频变压器的串联开关电源的设想，这对电源向体积和重量的下降获得了一条根本的途径。

开关电源外文翻译()————————————————————————————————作者：————————————————————————————————日期：Modeling, Simulation, and Reduction of Conducted Electromagnetic Interference Due to a PWM Buck Type Switching Power Supply IA. FarhadiAbstract:Undesired generation of radiated or conducted energy in electrical systems is called Electromagnetic Interference (EMI). High speed switching frequency in power electronics converters especially in switching power supplies improves efficiency but leads to EMI. Different kind of conducted interference, EMI regulations and conducted EMI measurement are introduced in this paper. Compliancy with national or international regulation is called Electromagnetic Compatibility (EMC). Power electronic systems producers must regard EMC. Modeling and simulation is the first step of EMC evaluation. EMI simulation results due to a PWM Buck type switching power supply are presented in this paper. To improve EMC, some techniques are introduced and their effectiveness proved by simulation.Index Terms:Conducted, EMC, EMI, LISN, Switching SupplyI. INTRODUCTIONFAST semiconductors make it possible to have high speed and high frequency switching in power electronics []1. High speed switching causes weight and volume reduction of equipment, but some unwanted effects such as radio frequency interference appeared []2. Compliance with electromagnetic compatibility (EMC) regulations is necessary for producers to present their products to the markets. It is important to take EMC aspects already in design phase []3. Modeling and simulation is the most effective tool to analyze EMC consideration before developing the products. A lot of the previous studies concerned the low frequency analysis of power electronics components []4[]5. Different types of power electronics converters are capable to be considered as source of EMI. They could propagate the EMI in both radiated and conducted forms. Line Impedance Stabilization Network (LISN) is required for measurement and calculation of conducted interference level []6. Interference spectrum at the output of LISN is introduced as the EMC evaluation criterion []7[]8. National or international regulations are the references for the evaluation of equipment in point of view of EMC []7[]8.II. SOURCE, PATH AND VICTIM OF EMIUndesired voltage or current is called interference and their cause is called interferencesource. In this paper a high-speed switching power supply is the source of interference.Interference propagated by radiation in area around of an interference source or by conduction through common cabling or wiring connections. In this study conducted emission is considered only. Equipment such as computers, receivers, amplifiers, industrial controllers, etc that are exposed to interference corruption are called victims. The common connections of elements, source lines and cabling provide paths for conducted noise or interference. Electromagnetic conducted interference has two components as differential mode and common mode []9.A. Differential mode conducted interferenceThis mode is related to the noise that is imposed between different lines of a test circuit by a noise source. Related current path is shown in Fig. 1 []9. The interference source, path impedances, differential mode current and load impedance are also shown in Fig. 1.B. Common mode conducted interferenceCommon mode noise or interference could appear and impose between the lines, cables or connections and common ground. Any leakage current between load and common ground could be modeled by interference voltage source.and Fig. 2 demonstrates the common mode interference source, common mode currents Icm1 and the related current paths[]9.The power electronics converters perform as noise source Icm2between lines of the supply network. In this study differential mode of conducted interference is particularly important and discussion will be continued considering this mode only.III. ELECTROMAGNETIC COMPATIBILITY REGULATIONS Application of electrical equipment especially static power electronic converters in different equipment is increasing more and more. As mentioned before, power electronics converters are considered as an important source of electromagnetic interference and have corrupting effects on the electric networks []2. High level of pollution resulting from various disturbances reduces the quality of power in electric networks. On the other side some residential, commercial and especially medical consumers are so sensitive to power system disturbances including voltage and frequency variations. The best solution to reduce corruption and improve power quality is complying national or international EMC regulations. CISPR, IEC, FCC and VDE are among the most famous organizations from Europe, USA and Germany who are responsible for determining and publishing the most important EMC regulations. IEC and VDE requirement and limitations on conducted emission are shown in Fig. 3 and Fig. 4 []7[]9.For different groups of consumers different classes of regulations could be complied. Class A for common consumers and class B with more hard limitations for special consumers are separated in Fig. 3 and Fig. 4. Frequency range of limitation is different for IEC and VDE that are 150 kHz up to 30 MHz and 10 kHz up to 30 MHz respectively. Compliance of regulations isevaluated by comparison of measured or calculated conducted interference level in the mentioned frequency range with the stated requirements in regulations. In united European community compliance of regulation is mandatory and products must have certified label to show covering of requirements []8.IV. ELECTROMAGNETIC CONDUCTED INTERFERENCE MEASUREMENTA. Line Impedance Stabilization Network (LISN)1-Providing a low impedance path to transfer power from source to power electronics converter and load.2-Providing a low impedance path from interference source, here power electronics converter, to measurement port.Variation of LISN impedance versus frequency with the mentioned topology is presented inFig. 7. LISN has stabilized impedance in the range of conducted EMI measurement []7.Variation of level of signal at the output of LISN versus frequency is the spectrum of interference. The electromagnetic compatibility of a system can be evaluated by comparison of its interference spectrum with the standard limitations. The level of signal at the output of LISN in frequency range 10 kHz up to 30 MHz or 150 kHz up to 30 MHz is criterion of compatibility and should be under the standard limitations. In practical situations, the LISN output is connected to a spectrum analyzer and interference measurement is carried out. But for modeling and simulation purposes, the LISN output spectrum is calculated using appropriate software.For a simple fixed frequency PWM controller that is applied to a Buck DC/DC converter, it is) changes slow with respect to the switching frequency, the possible to assume the error voltage (vepulse width and hence the duty cycle can be approximated by (1). Vp is the saw tooth waveform amplitude.A. PWM waveform spectral analysisThe normalized pulse train m (t) of Fig. 8 represents PWM switch current waveform. The nth pulse of PWM waveform consists of a fixed component D/fs , in which D is the steady state duty cycle, and a variable component dn/f sthat represents the variation of duty cycle due to variation of source, reference and load.As the PWM switch current waveform contains information concerning EMI due to powersupply, it is required to do the spectrum analysis of this waveform in the frequency range of EMI studies. It is assumed that error voltage varies around V e with amplitude of V e1 as is shown in (2).fm represents the frequency of error voltage variation due to the variations of source, reference and load. The interception of the error voltage variation curve and the saw tooth waveform with switching frequency, leads to (3) for the computation of duty cycle coefficients []10.Maximum variation of pulse width around its steady state value of D is limited to D1. In each period of Tm=1/fm , there will be r=fs/fm pulses with duty cycles of dn. Equation (4) presents the Fourier series coefficients Cn of the PWM waveform m (t). Which have the frequency spectrum of Fig.9.B-Equivalent noise circuit and EMI spectral analysisTo attain the equivalent circuit of Fig.6 the voltage source Vs is replaced by short circuit and) as it has shown in Fig. 10. converter is replaced by PWM waveform switch current (IexThe transfer function is defined as the ratio of the LISN output voltage to the EMI current source as in (5).The coefficients di, ni (i = 1, 2, … , 4) correspond to the parameters of the equivalent circuit. Rc and Lc are respectively the effective series resistance (ESR) and inductance (ESL) of the filter capacitor Cf that model the non-ideality of this element. The LISN and filter parameters are as follows: CN = 100 nF, r = 5 Ω, l = 50 uH, RN =50 Ω, LN=250 uH, Lf = 0, Cf =0, Rc= 0, Lc= 0, fs =25 kHzThe EMI spectrum is derived by multiplication of the transfer function and the source noise spectrum. Simulation results are shown in Fig. 11.VI. PARAMETERS AFFECTION ON EMIA. Duty CycleThe pulse width in PWM waveform varies around a steady state D=0.5. The output noise spectrum was simulated with values of D=0.25 and 0.75 that are shown in Fig. 12 and Fig. 13. Even harmonics are increased and odd ones are decreased that is desired in point of view of EMC.On the other hand the noise energy is distributed over a wider range of frequency and the level of EMI decreased []11.B. Amplitude of duty cycle variationThe maximum pulse width variation is determined by D1. The EMI spectrum was simulatedwith D1=0.05. Simulations are repeated with D1=0.01 and 0.25 and the results are shown in Fig.14and Fig.15.Increasing of D1 leads to frequency modulation of the EMI signal and reduction in level of conducted EMI. Zooming of Fig. 15 around 7th component of switching frequency in Fig. 16 shows the frequency modulation clearly.C. Error voltage frequencyThe main factor in the variation of duty cycle is the variation of source voltage. The fm=100 Hz ripple in source voltage is the inevitable consequence of the usage of rectifiers. The simulation is repeated in the frequency of fm=5000 Hz. It is shown in Fig. 17 that at a higher frequency for fm the noise spectrum expands in frequency domain and causes smaller level of conducted EMI. On the other hand it is desired to inject a high frequency signal to the reference voltage intentionally.D. Simultaneous effect of parametersSimulation results of simultaneous application of D=0.75, D1=0.25 and fm=5000 Hz that leadto expansion of EMI spectrum over a wider frequencies and considerable reduction in EMI level is shown in Fig. 18.VII. CONCLUSIONAppearance of Electromagnetic Interference due to the fast switching semiconductor devices performance in power electronics converters is introduced in this paper. Radiated and conducted interference are two types of Electromagnetic Interference where conducted type is studied in this paper. Compatibility regulations and conducted interference measurement were explained. LISN as an important part of measuring process besides its topology, parameters and impedance were described. EMI spectrum due to a PWM Buck type DC/DC converter was considered and simulated. It is necessary to present mechanisms to reduce the level of Electromagnetic interference. It shown that EMI due to a PWM Buck type switching power supply could be reduced by controlling parameters such as duty cycle, duty cycle variation and reference voltage frequency.VIII. REFRENCES[1] Mohan, Undeland, and Robbins, “Power Electronics Converters, Applications and Design” 3rdedition, John Wiley & Sons, 2003.[2] P. Moy, “EMC Related Issues for Power Electronics”, IEEE, Automotive Pow er Electronics, 1989, 28-29 Aug. 1989 pp. 46 – 53.[3] M. J. Nave, “Prediction of Conducted Interference in Switched Mode Power Supplies”, Session 3B, IEEE International Symp. on EMC, 1986.[4] Henderson, R. D. and Rose, P. J., “Harmonics and their Effec ts on Power Quality and Transformers”, IEEE Trans. On Ind. App., 1994, pp. 528-532.[5] I. Kasikci, “A New Method for Power Factor Correction and Harmonic Elimination in Power System”, Proceedings of IEEE Ninth International Conference on Harmonics and Q uality of Power, Volume 3, pp. 810 – 815, Oct. 2000.[6] M. J. Nave, “Line Impedance Stabilization Networks: Theory and Applications”, RFI/EMI Corner, April 1985, pp. 54-56.[7] T. Williams, “EMC for Product Designers” 3rd edition 2001 Newnes.[8] B. Ke isier, “Principles of Electromagnetic Compatibility”, 3rd edition ARTECH HOUSE 1987.[9] J. C. Fluke, “Controlling Conducted Emission by Design”, Vanhostrand Reinhold 1991.[10] M. Daniel,”DC/DC Switching Regulator Analysis”, McGrawhill 1988[11] M. J. Nave,” The Effect of Duty Cycle on SMPS Common Mode Emission: theory and experiment”, IEEE National Symposium on Electromagnetic Compatibility, Page(s): 211-216, 23-25 May 1989.作者：A. Farhadi国籍：伊朗出处：基于压降型PWM开关电源的建模、仿真和减少传导性电磁干扰IIA. Farhadi作者：A. Farhadi国籍：伊朗出处：摘要：电子设备之中杂乱的辐射或者能量叫做电磁干扰(EMI)。

外文文献Switched-mode power supplyA switched-mode power supply (also switching-mode power supply, SMPS, or simply switcher) is an electronic power supply unit (PSU) that incorporates a switching regulator. While a linear regulator maintains the desired output voltage by dissipating excess power in a pass power transistor, the switched-mode power supply switches a power transistor between saturation (full on) and cutoff (completely off) with a variable duty cycle whose average is the desired output voltage. It switches at a much-higher frequency (tens to hundreds of kHz) than that of the AC line (mains), which means that the transformer that it feeds can be much smaller than one connected directly to the line/mains. Switching creates a rectangular waveform that typically goes to the primary of the transformer; typically several secondaries feed rectifiers, series inductors, and filter capacitors to provide various DC outputs with low ripple.The main advantage of this method is greater efficiency because the switching transistor dissipates little power in the saturated state and the off state compared to the semiconducting state (active region). Other advantages include smaller size and lighter weight (from the elimination of low frequency transformers which have a high weight) and lower heat generation due to higher efficiency. Disadvantages include greater complexity, the generation of high amplitude, high frequency energy that the low-pass filter must block to avoid electromagnetic interference (EMI), and a ripple voltage at the switching frequency and the harmonic frequencies thereof.A note about terminologyAlthough the term "power supply" has been in use since radios were first powered from the line/mains, that does not mean that it is a source of power, in thesense that a battery provides power. It is simply a device that (usually) accepts commercial AC power and provides one or more DC outputs. It would be more correctly referred to as a power converter, but long usage has established the term.ClassificationSMPS can be classified into four types according to the input and output waveforms:AC in, DC out: rectifier, off-line converter input stageDC in, DC out: voltage converter, or current converter, or DC to DC converter AC in, AC out: frequency changer, cycloconverter, transformerDC in, AC out: inverterInput rectifier stageIf the SMPS has an AC input, then the first stage is to convert the input to DC. This is called rectification. The rectifier circuit can be configured as a voltage doubler by the addition of a switch operated either manually or automatically. This is a feature of larger supplies to permit operation from nominally 120 volt or 240 volt supplies. The rectifier produces an unregulated DC voltage which is then sent to a large filter capacitor. The current drawn from the mains supply by this rectifier circuit occurs in short pulses around the AC voltage peaks. These pulses have significant high frequency energy which reduces the power factor. Special control techniques can be employed by the following SMPS to force the average input current to follow the sinusoidal shape of the AC input voltage thus the designer should try correcting the power factor. An SMPS with a DC input does not require this stage. An SMPS designed for AC input can often be run from a DC supply (for 230V AC this would be 330V DC), as the DC passes through the rectifier stage unchanged. It's however advisable to consult the manual before trying this, though most supplies are quite capable of such operation even though nothing is mentioned in the documentation.However, this type of use may be harmful to the rectifier stage as it will only utilize half of diodes in the rectifier for the full load. This may result in overheating of these components, and cause them to fail prematurely.If an input range switch is used, the rectifier stage is usually configured to operate as a voltage doubler when operating on the low voltage (~120 V AC) range and as a straight rectifier when operating on the high voltage (~240 V AC) range. If an input range switch is not used, then a full-wave rectifier is usually used and the downstream inverter stage is simply designed to be flexible enough to accept the wide range of dc voltages that will be produced by the rectifier stage. In higher-power SMPSs, some form of automatic range switching may be used.Inverter stageThe inverter stage converts DC, whether directly from the input or from the rectifier stage described above, to AC by running it through a power oscillator, whose output transformer is very small with few windings at a frequency of tens or hundreds of kilohertz (kHz). The frequency is usually chosen to be above 20 kHz, to make it inaudible to humans. The output voltage is optically coupled to the input and thus very tightly controlled. The switching is implemented as a multistage (to achieve high gain) MOSFET amplifier. MOSFETs are a type of transistor with a low on-resistance and a high current-handling capacity. Since only the last stage has a large duty cycle, previous stages can be implemented by bipolar transistors leading to roughly the same efficiency. The second last stage needs to be of a complementary design, where one transistor charges the last MOSFET and another one discharges the MOSFET. A design using a resistor would run idle most of the time and reduce efficiency. All earlier stages do not weight into efficiency because power decreases by a factor of 10 for every stage (going backwards) and thus the earlier stages are responsible for at most 1% of the efficiency. This section refers to the block marked Chopper in theblock diagram.V oltage converter and output rectifierIf the output is required to be isolated from the input, as is usually the case in mains power supplies, the inverted AC is used to drive the primary winding of a high-frequency transformer. This converts the voltage up or down to the required output level on its secondary winding. The output transformer in the block diagram serves this purpose.If a DC output is required, the AC output from the transformer is rectified. For output voltages above ten volts or so, ordinary silicon diodes are commonly used. For lower voltages, Schottky diodes are commonly used as the rectifier elements; they have the advantages of faster recovery times than silicon diodes (allowing low-loss operation at higher frequencies) and a lower voltage drop when conducting. For even lower output voltages, MOSFETs may be used as synchronous rectifiers; compared to Schottky diodes, these have even lower conducting state voltage drops.The rectified output is then smoothed by a filter consisting of inductors and capacitors. For higher switching frequencies, components with lower capacitance and inductance are needed.Simpler, non-isolated power supplies contain an inductor instead of a transformer. This type includes boost converters, buck converters, and the so called buck-boost converters. These belong to the simplest class of single input, single output converters which utilize one inductor and one active switch. The buck converter reduces the input voltage in direct proportion to the ratio of conductive time to the total switching period, called the duty cycle. For example an ideal buck converter with a 10 V input operating at a 50% duty cycle will produce an average output voltage of 5 V. A feedback control loop is employed to regulate the output voltage by varying the duty cycle to compensate for variations in input voltage. Theoutput voltage of a boost converter is always greater than the input voltage and the buck-boost output voltage is inverted but can be greater than, equal to, or less than the magnitude of its input voltage. There are many variations and extensions to this class of converters but these three form the basis of almost all isolated and non-isolated DC to DC converters. By adding a second inductor the Ćuk and SEPIC converters can be implemented, or, by adding additional active switches, various bridge converters can be realised.Other types of SMPSs use a capacitor-diode voltage multiplier instead of inductors and transformers. These are mostly used for generating high voltages at low currents (Cockcroft-Walton generator). The low voltage variant is called charge pump.RegulationA feedback circuit monitors the output voltage and compares it with a reference voltage, which is set manually or electronically to the desired output. If there is an error in the output voltage, the feedback circuit compensates by adjusting the timing with which the MOSFETs are switched on and off. This part of the power supply is called the switching regulator. The Chopper controller shown in the block diagram serves this purpose. Depending on design/safety requirements, the controller may or may not contain an isolation mechanism (such as opto-couplers) to isolate it from the DC output. Switching supplies in computers, TVs and VCRs have these opto-couplers to tightly control the output voltage.Open-loop regulators do not have a feedback circuit. Instead, they rely on feeding a constant voltage to the input of the transformer or inductor, and assume that the output will be correct. Regulated designs compensate for the parasitic capacitance of the transformer or coil. Monopolar designs also compensate for the magnetic hysteresis of the core.The feedback circuit needs power to run before it can generate power, so an additional non-switching power-supply for stand-by is added.Transformer designSMPS transformers run at high frequency. Most of the cost savings (and space savings) in off-line power supplies come from the fact that a high frequency transformer is much smaller than the 50/60 Hz transformers formerly used.There are several differences in the design of transformers for 50 Hz vs 500 kHz. Firstly a low frequency transformer usually transfers energy through its core (soft iron), while the (usually ferrite) core of a high frequency transformer limits leakage. Since the waveforms in a SMPS are generally high speed (PWM square waves), the wiring must be capable of supporting high harmonics of the base frequency due to the skin effect, which is a major source of power loss.Power factorSimple off-line switched mode power supplies incorporate a simple full wave rectifier connected to a large energy storing capacitor. Such SMPSs draw current from the AC line in short pulses when the mains instantaneous voltage exceeds the voltage across this capacitor. During the remaining portion of the AC cycle the capacitor provides energy to the power supply.As a result, the input current of such basic switched mode power supplies has high harmonic content and relatively low power factor. This creates extra load on utility lines, increases heating of the utility transformers and standard AC electric motors, and may cause stability problems in some applications such as in emergency generator systems or aircraft generators. Harmonics can be removed through the use of filter banks but the filtering is expensive, and the power utility may require a business with a very low power factor to purchase and install the filtering onsite.In 2001 the European Union put into effect the standard IEC/EN61000-3-2 to setlimits on the harmonics of the AC input current up to the 40th harmonic for equipment above 75 W. The standard defines four classes of equipment depending on its type and current waveform. The most rigorous limits (class D) are established for personal computers, computer monitors, and TV receivers. In order to comply with these requirements modern switched-mode power supplies normally include an additional power factor correction (PFC) stage.Putting a current regulated boost chopper stage after the off-line rectifier (to charge the storage capacitor) can help correct the power factor, but increases the complexity (and cost).Quasiresonant ZCS/ZVSA quasiresonant ZCS/ZVS switch (Zero Current/Zero V oltage) is a design where "each switch cycle delivers a quantized 'packet' of energy to the converter output, and switch turn-on and turn-off occurs at zero current and voltage, resulting in an essentially lossless switch."EfficiencyHigher input voltage and synchronous rectification mode makes the conversion process more efficient. Higher switch frequency allows component size to be shrunk, but suffer from radio frequency (RF) properties on the other hand. The power consumption of the controller also has to be taken into account.ApplicationsSwitched-mode PSUs in domestic products such as personal computers often have universal inputs, meaning that they can accept power from most mains supplies throughout the world, with rated frequencies from 50 Hz to 60 Hz and voltages from 100 V to 240 V (although a manual voltage range switch may be required). In practice they will operate from a much wider frequency range and often from a DC supply as well. In 2006, at an Intel Developers Forum, Google engineers proposed theuse of a single 12 V supply inside PCs, due to the high efficiency of switch mode supplies directly on the PCB.Most modern desktop and laptop computers already have a DC-DC converter on the motherboard, to step down the voltage from the PSU or the battery to the CPU core voltage, as low as V for a low voltage CPU to V for a desktop CPU as of 2007. Most laptop computers also have a DC-AC inverter to step up the voltage from the battery to drive the backlight, typically around 1000 Vrms.Certain applications, such as in automobile industry where ordinary cars often use 12 V DC and in some industrial settings, DC supply is chosen to avoid hum and interference and ease the integration of capacitors and batteries used to buffer the voltage. Most small aircraft use 28 V DC, but larger aircraft like Boeing-747 often use up to 90 kV A 3-phase at 200 V AC 400 Hz, though they often have a DC bus as well. Even fighter planes like F-16 use 400 Hz power. The MD-81 airplane has an 115/200 V 400 Hz AC and 28 V DC power system generated by three 40 kV A AC generators. Helicopters also use the 28 V DC system. Some submarines like the Soviet Alfa class submarine utilized two synchronous generators providing a variable three-phase current, 2 x 1500 kW, 400 V, 400 Hz. The space shuttle uses three fuel cells generating 30 - 36 V DC. Some is converted into 400 Hz AC power and 28 V DC power. The International Space Station uses 120 V DC power. Larger trucks uses 24 V DC.See also: Avionics, Airplane ground supportIn the case of TV sets, for example, one can test the excellent regulation of the power supply by using a variac. For example, in some models made by Philips, the power supply starts when the voltage reaches around 90 volts. From there, one can change the voltage with the variac, and go as low as 40 volts and as high as 260 (known such case that voltage was 360), and the image will show absolutely no alterations.TerminologyThe term switchmode was widely used until Motorola trademarked SWITCHMODE(TM), for products aimed at the switching-mode power supply market, and started to enforce their trademark.外文翻译开关模式电源开关模式电源（也开关式电源，开关电源，或只是交换机）是一种电子电源供应器（电源），包含了开关稳压器。

Pulse Width Modulator (PWM) General-Purpose TimersPWMPulse width modulation (PWM) is a powerful technique for digitally encoding analog signal levels.High-resolution counters are used to generate a square wave, and the duty cycle of the squarewave is modulated to encode an analog signal. Typical applications include switching power suppliesand motor control.The Stellaris® PWM module consists of three PWM generator blocks and a control block. The controlblock determines the polarity of the PWM signals, and which signals are passed through to the pins.Each PWM generator block produces two PWM signals that can either be independent signals(other than being based on the same timer and therefore having the same frequency) or a singlepair of complementary signals with dead-band delays inserted. The output of the PWM generationblocks are managed by the output control block before being passed to the device pins.The Stellaris® PWM module provides a great deal of flexibility. It can generate simple PWM signals,such as those required by a simple charge pump. It can also generate paired PWM signals withdead-band delays, such as those required by a half-H bridge driver. Three generator blocks canalso generate the full six channels of gate controls required by a 3-phase inverter bridge.PWM TimerThe timer in each PWM generator runs in one of two modes: Count-Down mode or Count-Up/Downmode. In Count-Down mode, the timer counts from the load value to zero, goes back to the loadvalue, and continues counting down. In Count-Up/Down mode, the timer counts from zero up to theload value, back down to zero, back up to the load value, and so on. Generally, Count-Down modeis used for generating left- or right-aligned PWM signals, while the Count-Up/Down mode is usedfor generating center-aligned PWM signals.The timers output three signals that are used in the PWM generation process: the direction signal(this is always Low in Count-Down mode, but alternates between Low and High in Count-Up/Downmode), a single-clock-cycle-width High pulse when the counter is zero, and a single-clock-cycle-widthHigh pulse when the counter is equal to the load value. Note that in Count-Down mode, the zeropulse is immediately followed by the load pulse.PWM ComparatorsThere are two comparators in each PWM generator that monitor the value of the counter; wheneither match the counter, they output a single-clock-cycle-width High pulse. When in Count-Up/Downmode, these comparators match both when counting up and when counting down; they are thereforequalified by the counter direction signal. These qualified pulses are used in the PWM generationprocess. If either comparator match value is greater than the counter load value, then that comparatornever outputs a High pulse.Figure 15-3 on page 493 shows the behavior of the counter and the relationship of these pulseswhen the counter is in Count-Down mode. Figure 15-4 on page 493 shows the behavior of the counterand the relationship of these pulses when the counter is in Count-Up/Down mode.PWM Signal GeneratorThe PWM generator takes these pulses (qualified by the direction signal), and generates two PWMsignals. In Count-Down mode, there are four events that can affect the PWM signal: zero, load,match A down, and match B down. In Count-Up/Down mode, there are six events that can affectthe PWM signal: zero, load, match A down, match A up, match B down, and match B up. The matchA or matchB events are ignored when they coincide with the zero or load events. If the match Aand match B events coincide, the first signal, PWMA, is generated based only on the match A event,and the second signal, PWMB, is generated based only on the match B event.Dead-Band GeneratorThe two PWM signals produced by the PWM generator are passed to the dead-band generator. Ifdisabled, the PWM signals simply pass through unmodified. If enabled, the second PWM signal islost and two PWM signals are generated based on the first PWM signal. The first output PWM signalis the input signal with the rising edge delayed by a programmable amount. The second outputPWM signal is the inversion of the input signal with a programmable delay added between the fallingedge of the input signal and the rising edge of this new signal.Interrupt/ADC-Trigger SelectorThe PWM generator also takes the same four (or six) counter events and uses them to generatean interrupt or an ADC trigger. Any of these events or a set of these events can be selected as asource for an interrupt; when any of the selected events occur, an interrupt is generated. Additionally,the same event, a different event, the same set of events, or a different set of events can be selectedas a source for an ADC trigger; when any of these selected events occur, an ADC trigger pulse isgenerated. The selection of events allows the interrupt or ADC trigger to occur at a specific positionwithin the PWM signal. Note that interrupts and ADC triggers are based on the raw events; delaysin the PWM signal edges caused by the dead-band generator are not taken into account.Synchronization MethodsThere is a global reset capability that can synchronously reset any or all of the counters in the PWMgenerators. If multiple PWM generators are configured with the same counter load value, this canbe used to guarantee that they also have the same count value (this does imply that the PWMgenerators must be configured before they are synchronized). With this, more than two PWM signalscan be produced with a known relationship between the edges of those signals since the countersalways have the same values.The counter load values and comparator match values of the PWM generator can be updated intwo ways. The first is immediate update mode, where a new value is used as soon as the counterreaches zero. By waiting for the counter to reach zero, a guaranteed behavior is defined, and overlyshort or overly long output PWM pulses are prevented.The other update method is synchronous, where the new value is not used until a global synchronizedupdate signal is asserted, at which point the new value is used as soon as the counter reacheszero. This second mode allows multiple items in multiple PWM generators to be updatedsimultaneously without odd effects during the update; everything runs from the old values until apoint at which they all run from the new values. The Update mode of the load and comparator matchvalues can be individually configured in each PWM generator block. It typically makes sense to usethe synchronous update mechanism across PWM generator blocks when the timers in those blocksare synchronized, though this is not required in order for this mechanism to function properly.Fault ConditionsThere are two external conditions that affect the PWM block; the signal input on the Fault pin andthe stalling of the controller by a debugger. There are two mechanisms available to handle suchconditions: the output signals can be forced into an inactive state and/or the PWM timers can bestopped.Each output signal has a fault bit. If set, a fault input signal causes the corresponding output signalto go into the inactive state. If the inactive state is a safe condition for the signal to be in for anextended period of time, thiskeeps the output signal from driving the outside world in a dangerousmanner during the fault condition. A fault condition can also generate a controller interrupt.Each PWM generator can also be configured to stop counting during a stall condition. The user canselect for the counters to run until they reach zero then stop, or to continue counting and reloading.A stall condition does not generate a controller interrupt.Output Control BlockWith each PWM generator block producing two raw PWM signals, the output control block takescare of the final conditioning of the PWM signals before they go to the pins. Via a single register,the set of PWM signals that are actually enabled to the pins can be modified; this can be used, forexample, to perform commutation of a brushless DC motor with a single register write (and withoutmodifying the individual PWM generators, which are modified by the feedback control loop). Similarly,fault control can disable any of the PWM signals as well. A final inversion can be applied to any ofthe PWM signals, making them active Low instead of the default active High.General-Purpose TimersProgrammable timers can be used to count or time external events that drive the Timer input pins.The Stellaris? General-Purpose Timer Module (GPTM) contains three GPTM blocks (Timer0, Timer1,and Timer 2). Each GPTM block provides two 16-bit timers/counters (referred to as TimerA andTimerB) that can be configured to operate independently as timers or event counters, or configuredto operate as one 32-bit timer or one 32-bit Real-Time Clock (RTC).In addition, timers can be used to trigger analog-to-digital conversions (ADC). The ADC triggersignals from all of the general-purpose timers are ORed together before reaching the ADC module,so only one timer should be used to trigger ADC events.The GPT Module is one timing resource available on the Stellaris? microcontrollers. Other timerresources include the System Timer (SysTick) and the PWM timer in thePWM module.The General-Purpose Timers provide the following features:■Three General-Purpose Timer Modules (GPTM), each of which provides two 16-bittimers/counters. Each GPTM can be configured to operate independently:–As a single 32-bit timer–As one 32-bit Real-Time Clock (RTC) to event capture–For Pulse Width Modulation (PWM)–To trigger analog-to-digital conversions■32-bit Timer modes–Programmable one-shot timer–Programmable periodic timer–Real-Time Clock when using an external 32.768-KHz clock as the input–User-enabled stalling when the controller asserts CPU Halt flag during debug–ADC event trigger■16-bit Timer modes–General-purpose timer function with an 8-bit prescaler (for one-shot and periodic modes only)–Programmable one-shot timer–Programmable periodic timer–User-enabled stalling when the controller asserts CPU Halt flag during debug–ADC event trigger■16-bit Input Capture modes–Input edge count capture270 September 04, 2010Texas Instruments-Production DataGeneral-Purpose Timers–Input edge time capture■16-bit PWM mode–Simple PWM mode with software-programmable output inversion of the PWM signaFunctional DescriptionThe main components of each GPTM block are two free-running 16-bit up/down counters (referredto as TimerA and TimerB), two 16-bit match registers, two prescaler match registers, and two 16-bitload/initialization registers and their associated control functions. The exact functionality of eachGPTM is controlled by software and configured through the register interface.Software configures the GPTM using the GPTM Configuration (GPTMCFG) register,the GPTM TimerA Mode (GPTMTAMR) register and the GPTM TimerB Mode(GPTMTBMR) register. When in one of the 32-bit modes, the timer can only act asa 32-bit timer. However, when configured in 16-bit mode, the GPTM can have its two 16-bit timersconfigured in any combination of the 16-bit modes.8.2.1 GPTM Reset ConditionsAfter reset has been applied to the GPTM module, the module is in an inactive state, and all controlregisters are cleared and in their default states. Counters TimerA and TimerB are initialized to0xFFFF, along with their corresponding load registers: the GPTM TimerA Interval Load(GPTMTAILR) register (see page 296) and the GPTM TimerB Interval Load (GPTMTBILR) register. The prescale counters are initialized to 0x00: the GPTM TimerA Prescale(GPTMTAPR) register (see page 300) and the GPTM TimerB Prescale (GPTMTBPR) register.32-Bit Timer Operating ModesThis section describes the three GPTM 32-bit timer modes (One-Shot, Periodic, and RTC) and theirconfiguration.The GPTM is placed into 32-bit mode by writing a 0 (One-Shot/Periodic 32-bit timer mode) or a 1(RTC mode) to the GPTM Configuration (GPTMCFG) register. In both configurations, certain GPTMregisters are concatenated to form pseudo 32-bit registers. These registers include:■GPTM TimerA Interval Load (GPTMTAILR) register [15:0],■GPTM TimerB Interval Load (GPTMTBILR) register [15:0],■GPTM TimerA (GPTMTAR) register [15:0],■GPTM TimerB (GPTMTBR) register [15:0],In the 32-bit modes, the GPTM translates a 32-bit write access to GPTMTAILR into a write accessto both GPTMTAILR and GPTMTBILR. The resulting word ordering for such a write operation is: GPTMTBILR[15:0]:GPTMTAILR[15:0]Likewise, a read access to GPTMTAR returns the value:GPTMTBR[15:0]:GPTMTAR[15:0]8.2.2.1 32-Bit One-Shot/Periodic Timer ModeIn 32-bit one-shot and periodic timer modes, the concatenated versions of the TimerA and TimerBregisters are configured as a 32-bit down-counter. The selection of one-shot or periodic mode isdetermined by the value written to the TAMR field of the GPTM TimerA Mode (GPTMTAMR) register, and there is no need to write to the GPTM TimerB Mode (GPTMTBMR) register.When software writes the TAEN bit in the GPTM Control (GPTMCTL) register, theimer begins counting down from its preloaded value. Once the 0x0000.0000 state is reached, thetimer reloads its start value from the concatenated GPTMTAILR on the next cycle. If configured tobe a one-shot timer, the timer stops counting and clears the TAEN bit in the GPTMCTL register. Ifconfigured as a periodic timer, it continues counting.In addition to reloading the count value, the GPTM generates interrupts and triggers when it reachesthe 0x000.0000 state. The GPTM sets the TATORIS bit in the GPTM Raw Interrupt Status(GPTMRIS) register andholds it until it is cleared by writing the GPTM InterruptClear (GPTMICR) register. If the time-out interrupt is enabled in the GPTM InterruptMask (GPTMIMR) register (see page 290), the GPTM also sets the TATOMIS bit in the GPTM MaskedInterrupt Status (GPTMMIS) register (see page 293). The ADC trigger is enabled by setting theTAOTE bit in GPTMCTL.If software reloads the GPTMTAILR register while the counter is running, the counter loads the newvalue on the next clock cycle and continues counting from the new value.If the TASTALL bit in the GPTMCTL register is set, the timer freezes counting while the processoris halted by the debugger. The timer resumes counting when the processor resumes execution.32-Bit Real-Time Clock Timer ModeIn Real-Time Clock (RTC) mode, the concatenated versions of the TimerA and TimerB registersare configured as a 32-bit up-counter. When RTC mode is selected for the first time, the counter isloaded with a value of 0x0000.0001. All subsequent load values must be written to the GPTM TimerAMatch (GPTMTAMATCHR) register by the controller.The input clock on an even CCP input is required to be 32.768 KHz in RTC mode. The clock signalis then divided down to a 1 Hz rate and is passed along to the input of the 32-bit counter.When software writes the TAEN bit inthe GPTMCTL register, the counter starts counting up from itspreloaded value of 0x0000.0001. When the current count value matches the preloaded value in theGPTMTAMA TCHR register, it rolls over to a value of 0x0000.0000 and continues counting untileither a hardware reset, or it is disabled by software (clearing the TAEN bit). When a match occurs,the GPTM asserts the RTCRIS bit in GPTMRIS. If the RTC interrupt is enabled in GPTMIMR, theGPTM also sets the RTCMIS bit in GPTMMIS and generates a controller interrupt. The status flagsare cleared by writing the RTCCINT bit in GPTMICR.If the TASTALL and/or TBSTALL bits in the GPTMCTL register are set, the timer does not freeze ifthe RTCEN bit is set in GPTMCTL.16-Bit Timer Operating ModesThe GPTM is placed into global 16-bit mode by writing a value of 0x4 to the GPTM Configuration(GPTMCFG) register. This section describes each of the GPTM 16-bit modes ofoperation. TimerA and TimerB have identical modes, so a single description is given using an n toreference both.16-Bit One-Shot/Periodic Timer ModeIn 16-bit one-shot and periodic timer modes, the timer is configured as a 16-bit down-counter withan optional 8-bit prescaler that effectively extends the counting range of the timer to 24 bits. Theselection of one-shot or periodic mode is determined by the value written to the TnMR field of theGPTMTnMR register. The optional prescaler is loaded into the GPTM Timern Prescale (GPTMTnPR)register.When software writes the TnEN bit in the GPTMCTL register, the timer begins counting down fromits preloaded value. Once the 0x0000 state is reached, the timer reloads its start value froGPTMTnILR and GPTMTnPR on the next cycle. If configured to be a one-shot timer, the timer stopscounting and clears the TnEN bit in the GPTMCTL register. If configured as a periodic timer, itcontinues counting.In addition to reloading the count value, the timer generates interrupts and triggers when it reachesthe 0x0000 state. The GPTM sets the TnTORIS bit in the GPTMRIS register, and holds it until it iscleared by writing the GPTMICR register. If the time-out interrupt is enabled in GPTMIMR, the GPTMalso sets the TnTOMIS bit in GPTMISR and generates a controller interrupt. The ADC trigger isenabled by setting the TnOTE bit in the GPTMCTL register.If software reloads the GPTMTAILR register while the counter is running, the counter loads the newvalue on the next clock cycle and continues counting from the new value.If the TnSTALL bit in the GPTMCTL register is set, the timer freezes counting while the processoris halted by the debugger. The timer resumes counting when the processor resumes execution.16-Bit Input Edge Count ModeIn Edge Count mode, the timer is configured as a down-counter capable of capturing three typesof events: rising edge, falling edge, or both. To place the timer in Edge Count mode, the TnCMR bitof the GPTMTnMR register must be set to 0. The type of edge that in theGPTMTnILR register and the GPTMTnMA TCHR register equals the number of edge events thatmust be counted.When software writes the TnEN bit in the GPTM Control (GPTMCTL) register, the timer is enabledfor event capture. Each input event on the CCP pin decrements the counter by 1 until the event countmatches GPTMTnMA TCHR. When the counts match, the GPTM asserts the CnMRIS bit in theGPTMRIS register (and the CnMMIS bit, if the interrupt is not masked).The counter is then reloaded using the value in GPTMTnILR, and stopped since the GPTMautomatically clears the TnEN bit in the GPTMCTL register. Once the event count has been reached,all further events are ignored until TnEN is re-enabled by software.16-Bit Input Edge Time ModeIn EdgeTime mode, the timer is configured as a free-running down-counter initialized to the valueloaded in the GPTMTnILR register (or 0xFFFF at reset). This mode allows for event capture ofeither rising or falling edges, but not both. The timer is placed into Edge Time mode by setting theTnCMR bit in the GPTMTnMR register, and the type of event that the timer captures is determinedby the TnEVENT fields of the GPTMCTL register.When software writes the TnEN bit in the GPTMCTL register, the timer is enabled for event capture.When the selected input event is detected, the current Tn counter value is captured in the GPTMTnRregister and is available to be read by the controller. The GPTM then asserts the CnERIS bit (andthe CnEMIS bit, if the interrupt is not masked).After an event has been captured, the timer does not stop counting. It continues to count until theTnEN bit is cleared. When the timer reaches the 0x0000 state, it is reloaded with the value from theGPTMTnILR register.16-Bit PWM ModeThe GPTM supports a simple PWM generation mode. In PWM mode, the timer is configured as adown-counter with a start value (and thus period) defined by GPTMTnILR. In this mode, the PWMfrequency and period are synchronous events and therefore guaranteed to be glitch free. PWMmode is enabled with the GPTMTnMR register by setting the TnAMS bit to 0x1, the TnCMR bit to0x0, and the TnMR field to 0x2.When software writes the TnEN bit in the GPTMCTL register, the counter begins counting downuntil it reaches the 0x0000 state. On the next counter cycle, the counter reloads its start value fromGPTMTnILR and continues counting until disabled by software clearing the TnEN bit in the GPTMCTLregister. No interrupts or status bits are asserted in PWM mode.The output PWM signal asserts when the counter is at the value of the GPTMTnILR register (itsstart state), and is deasserted when the counter value equals the value in the GPTM Timern MatchRegister (GPTMTnMATCHR). Software has the capability of inverting the output PWM signal bysetting the TnPWML bit in the GPTMCTL register.。

毕业设计(论文)外文资料翻译院（系）：电子信息工程学院专业：自动化班级：120427姓名：加如月学号：120406122外文出处：中国知网科技论文附件： 1.译文；2.原文；3.评分表2016年5 月Switching Power Supply DesignJ. M. LEISTEN , M. DOUBLE & L. HOBSONTo cite this article: J. M. LEISTEN , M. DOUBLE & L. HOBSON (1990) Switching Power Supply Designflyback , International Journal of Electronics, 69:3, 435-449, DOI:10.1080/00207219008920329To link to this article: /10.1080/00207219008920329Switching power supply work in high frequency, high pulse state, are analog circuits in a rather special kind. Cloth boards to follow the principle of high-frequency circuit wiring.yout:Pulse voltage connection as short as possible, including input switch connected to the transformer, output transformer to the rectifier tube cable. Pulse current loop as small as possible such as the input filter capacitor is returned to the transformer to the switch capacitor negative. Some out-ended output transformers are the output rectifier to the output capacitor back to transformer circuit X capacitor as close as possible to the input switching power supply, input lines should be avoided in parallel with other circuits, should be avoided. Y capacitor should be placed in the chassis ground terminal or FG connectors. A total of touch induction and transformer to maintain a certain distance in order to avoid magnetic coupling. Such as poor handling of feeling in between inductor and transformer plus a shield, over a number of EMC performance for power supply to the greater impact.General the output capacitor can be used the other two a close rectifier output terminal should be close to, can affect the power supply output ripple index, two small capacitor in parallel results should be better than using a large capacitor. Heating devices to maintain a certain distance, andelectrolytic capacitors to extend machine life, electrolytic capacitors is the switching power supply bottleneck life, such as transformers, power control, high power resistors and electrolytic to maintain the distance required between the electrolyte leaving space for heat dissipation , conditions permitting, may be placed in the inlet.Control part to pay attention to: Weak signal high impedance circuit connected to sample the feedback loop as short as in the processing as far as possible avoid interference, the current sampling signal circuits, in particular the current control circuit, easy to deal with some unexpected bad The accident, which had some skill, now to 3843 the circuit example shown in full time by observing the current waveform oscilloscope Mingxian superimposed spikes, Youyuganrao limited flow ratio design Zhi Dian low, Figure 1 there is no such phenomenon, there are switch drive signal circuit, switch resistance should be close to the switch driver can switch the work to improve the reliability of this and the high DC impedance voltage power MOSFET driver characteristics. Second, routingAlignment of current density: now the majority of electronic circuit board using insulated copper constitute tied. Common PCB copper thickness of 35μm, the alignment value can be obtained in accordance with 1A/mm experience the value of current density, the specific calculations can be found in textbooks. To ensure the alignment principles of mechanical strength should be greater than or equal to the width of 0.3mm (other non-power supply circuit board may be smaller minimum line width). PCB copper thickness of 70μm is also common in switching power supply, then the current density can be higher.Add that, now Changyong circuit board design tool design software generally items such as line width, line spacing, hole size and so dry plate Guo Jin Xing parameters can be set. In the design of circuit boards, design software automatically in accordance with the specifications, can save time, reduce some of the workload and reduce the error rate.Generally higher on the reliability of lines or line density wiring can be used double panel. Characterized by moderate cost, high reliability, to meet most applications.The ranks of some of the power module products are also used plywood, mainly to facilitate integration of power devices such as transformer inductance to optimize wiring, cooling and other power tube. Good consistency with the craft beautiful, transformer cooling good advantage, but its disadvantage is high cost, poor flexibility, only suitable for industrial mass production.Single-sided, the market circulation of almost universal switching power supply using single-sided circuit board, which has the advantage of lower costs in the design and production technology are also taken some measures to ensure its performance.Single PCB design today to talk about some experience, as a single panel with low cost, easy-to-manufacture features, the switching power supply circuit has been widely used, because of its side tied only copper, the device's electrical connections, mechanical fixation should rely on the copper layer, the processing must be careful.To ensure good performance of the mechanical structure welding, single-sided pad should be slightly larger to ensure that the copper and substrate tied good focus, and thus will not be shocked when the copper strip, broken off. General welding ring width should be greater than 0.3mm. Pad diameter should be slightly larger than the diameter of the device pins, but not too large, to ensure pin and pad by the solder connection between the shortest distance, plate hole size should not hinder the normal conditions for the degree of investigation, the pad diameter is generally greater than pin diameter 0.1-0.2mm. Multi-pin device to ensure a smooth investigation documents can also be larger.Electrical connection should be as wide as possible, in principle, should be larger than the width of pad diameter, special circumstances should be connected in line with the need to widen the intersection pad (commonly known as Generation tears), to avoid breaking certain conditions, line and pad. Principle of minimum line width should be greater than 0.5mm.Single-board components to be close to the circuit board. Need overhead cooling device to device and circuit board between the pins plus casing, can play a supporting device and increase the dual role of insulation to minimize or avoid external shocks on the pad and thepin junction impact and enhance the firmness of welding. Circuit board supporting the weight of large parts can increase the connection point, can enhance joint strength between the circuit board, such as transformers, power device heat sink.Single-sided welding pins without affecting the surface and the shell spacing of the prior conditions, it can be to stay longer, the advantage of increased strength of welded parts, increase weld area and immediately found a Weld phenomenon. Shear pin long legs, the welding force smaller parts. In Taiwan, the Japanese often use the device pins in the welding area and the circuit board was bent 45 degrees, and then welding process, its reasoning Ibid. Double panel today to talk about the design of some of the issues, in relatively high number of requests, or take the line density of the larger application environments using double-sided PCB, its performance and various indicators of a lot better than a single panel.Two-panel pad as holes have been high intensity metal processing, welding ring smaller than a single panel, the pad hole diameter slightly larger in diameter than pins, as in the welding process solder solution conducive to penetrate through the top hole solder pad to increase the welding reliability. But there is a disadvantage if the hole is too large, wave soldering tin when the jet impact in the lower part of the device may go up, have some flaws.High current handling of alignment, line width in accordance with pre-quote processing, such as the width is not enough to go online in general can be used to increase the thickness of tin plating solution, the method has a good variety of1. Will take the line set to pad property, so that when the circuit board manufacturing solder alignment will not be covered, the whole hot air normally be tin plated.2. In the wiring by placing pads, the pad is set to take in line shape, pay attention3. In the solder layer placed on line, this method is the most flexible, but not all PCB manufacturers will understand your intentions, needed captions. Place the line in the solder layer of the site will not coated solder tinning line several methods as above, to note that, if the alignment of a very wide all plated with tin in solder after thesolder will bond a lot and distribution is very uneven, affecting appearance. Article tin can be used generally slender width in the 1 ~ 1.5mm, length can be determined according to lines, tin part of the interval 0.5 ~ 1mmDouble-sided circuit board for the layout, the alignment provides a very selective, make wiring more reasonable. On the ground, the power ground and signal ground must be separated, the two to converge in filter capacitors, in order to avoid a large pulsed current through the signal ground connection instability caused by unexpected factors, the signal control circuit grounding point as far as possible, a skill, as far as possible the alignment of the non-grounded wiring layer in the same place, the last shop in another layer of earth. Output line through the filter capacitors, the general first, and then to the load, input line must also pass capacitor, to the transformer, the theoretical basis is to ripple through trip filter capacitor.V oltage feedback sampling, in order to avoid high current through the alignment of the feedback voltage on the sampling point must be the most peripheral power output to increase the load effect of target machine.Alignment change from a wiring layer to another wiring layer generally used hole connected, not through the pin pad device to achieve, because the plug in the device may be damaged when the relationship between this connection, there is current in every passage of 1A, at least two through-hole, through hole diameter is greater than the principle of 0.5mm, 0.8mm generally processed ensure reliability.Cooling devices, in some small power supply, the circuit board traces can be and cooling, characterized by the alignment as generous as possible to increase the cooling area is not coated solder, conditions can even be placed over holes, enhanced thermal conductivity .Today to talk about the aluminum plate in the switching power supply application and multilayer printed circuit in the switching power supply applications.Aluminum plate by its own structure, has the following characteristics: very good thermal conductivity, single Mianfu copper, the device can only be placed in tied copper surface, can not open electrical connection hole so as not to placejumper in accordance with a single panel.Aluminum plate is generally placed patch device, switch, the output rectifier heat conduction through the substrate to go out, very low thermal resistance, high reliability can be achieved. Transformer with planar chip structure, but also through substrate cooling, the temperature is lower than the conventional, the same size transformer with a large aluminum plate structure available output power. Aluminum plate jumper bridge approach can be used. Aluminum plate power are generally composed by the two PCB, another one to place the control circuit board, through the physical connection between the two boards is integrated.As the excellent thermal conductivity of aluminum plate, in a small amount of manual welding more difficult, solder cooling too fast and prone to problems of a simple and practical way of existing, an ironing ordinary iron (preferably temperature regulation function), over and iron for the last, fixed, and temperature to 150 ℃and above the aluminum plate on the iron, heating time, and then affix the components according to conventional methods and welding, soldering iron temperature is appropriate to the device easy to , is too high when the device may be damaged, or even copper strip aluminum plate, the temperature is too low welding effect is not good, to be flexible.Recent years, with the multi-layer circuit board applications in switching power supply circuit, printed circuit transformer makes it possible, due to multilayer, smaller spacing also can take advantage of Bianya Qi window section, the main circuit board can be re- Add 1-2 formed by the multilayer printed coil to use the window, the purpose of reducing circuit current density, due to adopt printed coil, reducing manual intervention, transformers consistency, surface structure, low leakage inductance, coupling good . Open-type magnetic core, good heat dissipation. Because of its many advantages, is conducive to mass production, it is widely used. But the research and development of large initial investment, not suitable for small-scale health.Switching power supply is divided into, two forms of isolation and non-isolated, isolated here mainly to talk about switching power supply topologies form below, non-specified,are to isolate the power. Isolated power supply in accordance with the structure of different forms, can be divided into two categories: a forward and flyback. Flyback transformer primary side means that when the Vice-edge conduction cut-off, transformer storage. Close of the primary, secondary side conduction, the energy released to the load of work status, general conventional flyback power multiplex, twin-tube is not common. Forward refers to the primary conduction in transformer secondary side while the corresponding output voltage is induced into the load, the direct transfer of energy through the transformer. According to specifications can be divided into conventional forward, including the single-transistor forward, Double Forward. Half-bridge, bridge circuits are all forward circuit.Forward and flyback circuits have their own characteristics in the process of circuit design to achieve optimal cost-effective, can be applied flexibly. Usually in the low-power flyback can be adopted. Slightly larger forward circuit can use a single tube, medium-power can use Double Forward circuit or half-bridge circuit, low-voltage push-pull circuit, and the half-bridge work in the same state. High power output, generally used bridge circuit, low voltage can be applied push-pull circuit.Flyback power supply because of its simple structure, and to cut the size of a similar size and transformer inductance, the power supply in the medium has been widely applied. Presentation referred to in some flyback power supply can do dozens of watts, output power exceeding 100 watts would be no advantage to them difficult. Under normal circumstances, I think so, but it can not be generalized, PI's TOP chips can do 300 watts, an article describes the flyback power supply can be on the KW, but not seen in kind. Power output and the output voltage level.Flyback power transformer leakage inductance is a critical parameter, because the power needs of the flyback transformer stored energy, to make full use of transformer core, the general must be open in the magnetic circuit air gap, the aim is to change the core hysteresis back line of the slope, so that transformers can withstand the impact of a large pulse current, which is not core into saturation non-linear state, the magnetic circuit in the highreluctance air gap in the state, generated in the magnetic flux leakage is much larger than completely closed magnetic circuit .Transformer coupling between the first pole is the key factor determining the leakage inductance, the coil to be very close as far as possible the first time, the sandwich can be used around the law, but this would increase the distributed capacitance transformer. Use core as core with a long window, can reduce the leakage inductance, such as the use of EE, EF, EER, PQ-based EI type magnetic core effective than good.The duty cycle of flyback power supplies, in principle, the maximum duty cycle of flyback power supply should be less than 0.5, otherwise not easy loop compensation may be unstable, but there are some exceptions, such as the U.S. PI has introduced the TOP series chip can work under the conditions of duty cycle is greater than 0.5.Duty cycle by the transformer turns ratio to determine former deputy side, I am an anti-shock view is, first determine the reflected voltage (output voltage reflected through the transformer coupling the primary voltage value), reflecting a certain voltage range of voltage increase is duty cycle increases, lower power loss. Reduce the reflected voltage duty cycle decreases, increases power loss. Of course, this is a prerequisite, when the duty cycle increases, it means that the output diode conduction time, in order to maintain output stability, more time will be to ensure that the output capacitor discharge current, the output capacitor will be under even greater high-frequency ripple current erosion, while increasing its heat, which in many circumstances is not allowed.Duty cycle increases, change the transformer turns ratio, transformer leakage inductance will increase, its overall performance change, when the leakage inductance energy large enough, can switch to fully offset the large account space to bring low-loss, no further increase when the meaning of duty, because the leakage inductance may even be too high against the peak voltage breakdown switch. Leakage inductance as large, may make the output ripple, and other electromagnetic indicators deteriorated. When the duty hours, the high RMS current through the switch, transformer primary current rms and lowered the converter efficiency, butcan improve the working conditions of the output capacitor to reduce fever. How to determine the transformer reflected voltage (duty cycle)Some netizens said switching power supply feedback loop parameter settings, work status analysis. Since high school mathematics is rather poor, "Automatic Control Theory," almost on the make-up, and for the door is still feeling fear, and now can not write a complete closed-loop system transfer function, zero for the system, the concept of feeling pole vague, see Bode plot is only about to see is a divergence or convergence, so the feedback compensation can not nonsense, but there are a number of recommendations. If you have some mathematical skills, and then have some time to learn then the University of textbooks, "Principles of Automatic Control" digest look carefully to find out, combined with practical switching power supply circuit, according to the work of state for analysis. Will be harvested, the Forum has a message, "coach feedback loop to study the design, debugging," in which CMG good answer, I think we can reference.Then today, on the duty cycle of flyback power supply (I am concerned about the reflected voltage, consistent with the duty cycle), the duty cycle with the voltage selection switch is related to some early flyback switching power supply using a low pressure tube, such as 600V or 650V AC 220V input power as a switch, perhaps when the production process, high pressure tubes, easy to manufacture, or low-pressure pipes are more reasonable conduction losses and switching characteristics, as this line reflected voltage can not be too high, otherwise the work order to switch the security context of loss of power absorbing circuit is quite impressive.Reflected voltage 600V tube proved not more than 100V, 650V tube reflected voltage not greater than 120V, the leakage inductance voltage spike when the tubes are clamped at 50V 50V working margin. Now that the MOS raise the level of manufacturing process control, flyback power supplies are generally used 700V or 750V or 800-900V the switch. Like this circuit, overvoltage capability against a number of switching transformer reflected voltage can be done a bit higher, the maximum reflected voltage in the 150V is appropriate, to obtain better overallperformance.TOP PI's recommendation for the 135V chipset with transient voltage suppression diode clamp. But his evaluation board generally reflected voltage to be lower than the value at around 110V. Both types have their advantages and disadvantages: Category: shortcomings against over-voltage, low duty cycle is small, a large pulse current transformer primary. Advantages: small transformer leakage inductance, electromagnetic radiation and low ripple index higher switch loss, the conversion efficiency is not necessarily lower than the second.The second category: a large number of shortcomings of power loss, a large number of transformer leakage inductance, the ripple worse. Advantages: Some strong against over-voltage, large duty cycle, lower transformer losses and efficiency higher.Reflected voltage flyback power supply and a determining factorReflected voltage flyback power supply with a parameter related to that is the output voltage, output voltage, the lower the larger the transformer turns ratio, the greater the transformer leakage inductance, switch to withstand higher voltage breakdown switch is possible to absorb power consumption is higher, has the potential to permanently absorb the circuit power device failure (particularly with transient voltage suppression diode circuits). In the design of low-voltage low-power flyback power output optimization process must be handled with care, its approach has several:1, using a large core of a power level lower leakage inductance, which can improve the low-voltage flyback power conversion efficiency, reduce losses, reduce output ripple and improve multi-output power of the cross regulation in general is common in household appliances with a switch power, such as CD-ROM drive, DVB set-top boxes.2, if the conditions were not increased core, can reduce the reflected voltage, reducing the duty cycle. Reduce the reflected voltage can reduce the leakage inductance but may reduce the power conversion efficiency, which is a contradiction between the two, must have an alternative process to find a suitable point, replace the transformer during the experiment can detect the transformer original side of the anti-peak voltage, peak voltage to minimize theanti-pulse width, and magnitude of the work safety margin increase converter. Generally reflected voltage 110V when appropriate.3, enhance the coupling, reducing losses, the introduction of new technologies, and the routing process, transformers to meet the security specifications will between the primary and secondary side to insulation measures, such as pad tape, plus side air insulation tape. These will affect the performance of transformer leakage inductance, the reality can be used in production around the primary winding secondary wrapping method. Or sub-system with a triple insulated wire wound to remove the insulation between the initial level, can enhance the coupling, even use wide copper winding.The article refers to low voltage output is less than or equal to 5V output, as this type of small power supply, my experience is that the power output of more than 20W output can use a forward, get the best value for money, of course, this is not the right decision , and personal habits, relationship between the application environment, the next time to talk about the flyback power supply with a magnetic core, magnetic circuit air gap opening some understanding, I hope you receive adequate guidance.Flyback power transformer core magnetization state at work in one way, it needs to open the air gap magnetic circuit, similar to the pulsating direct current sensor. Part of the magnetic coupling through the air gap. Why I understand the principle of open air gap as follows: As the power ferrite also has a similar rectangle of the operating characteristics (hysteresis loop), operating characteristics curve in the Y-axis magnetic induction (B), now the general production process saturation point in 400mT above, the general value in the design of this value should be more appropriate in the 200-300mT, X-axis magnetic field strength (H) the value of current intensity is proportional to the magnetization. Open magnetic circuit air gap equal to the magnetic hysteresis loop to the X axis tilt, in the same magnetic induction intensity, can withstand a greater magnetizing current, equivalent to core store more energy, this energy cut-off switch When spilled into the load through the transformer secondary circuit, flyback power core to open the air gap is twofold. One is to transfer more energy, and the second toprevent the core into saturation.Flyback Power Transformer magnetization state in one way, not only to pass through the magnetic coupling energy, is also responsible for input and output isolation voltage transform multiple roles. Therefore, the treatment gap need to be very careful, the air gap leakage inductance can become too large, increase the hysteresis loss, iron loss, copper loss increases, affecting the power of the whole performance. Air gap is too small has the potential to transformer core saturation, resulting in damage to powerThe so-called flyback power supply is continuous and discontinuous mode transformer working conditions, working in full load condition in the power transformer complete transfer, or incomplete transmission mode. General design of the working environment, conventional flyback power supply should work in continuous mode, this switch, circuit loss are relatively small, and can reduce the stress of work input and output capacitors, but that there are some exceptions.Requires in particular that: As the characteristics of the flyback power supply is also more suitable for design into a high-voltage power supply, and high-voltage power transformers generally work in discontinuous mode, I understand the need for as high voltage power supply output voltage of the rectifier diodes. Because of the manufacturing process characteristics, high-tension diode, reverse recovery time is long, low speed, the current continuous state, the diode has a positive bias in the recovery, reverse recovery energy loss is very large, is not conducive to converter performance increase, ranging from reduced conversion efficiency, rectifiers, severe fever, weight is even burnt rectifier. As in the intermittent mode, the diode is reverse biased under zero bias, loss can be reduced to a relatively low level. Therefore, high voltage power supply work in discontinuous mode, and the frequency can not be too high.Another type of flyback power supply work in the critical state, the general type of power supply work in FM, or FM-width-modulated dual-mode, a number of low-cost self-excitation power (RCC) is often used this form in order to ensure stable output transformer As the operating frequency, output current or input voltage change, close tothe fully loaded transformer is always maintained at between continuous and intermittent, this power is only suitable for small power output, otherwise the handling characteristics of electromagnetic compatibility will be a headacheFlyback switching power supply transformer should work in continuous mode, it required relatively large winding inductance, of course, is to some extent continuous, excessive pursuit of absolute continuity is not realistic, may need a great core, very much coil turns, accompanied by a large leakage inductance and distributed capacitance, worth the trouble. So how does this parameter to determine, through repeated practice, and analysis of peer design, I think, in the nominal voltage input, the output reached 50% and 60% transformer from intermittent, continuous state of transition to more appropriate. Or at the highest input voltage state, the full output, the transformer can transition to the continuous state on it.。

DC Switching Power Supply Protection TechnologyPosted:2006-2-26 10：57:00 visit：665 chinese Version Related NewsAbstract: The DC switching power supply protection system is proposed to protect the system design principles and machine protection measures, analysis of switching power supply in the range of protected characteristics and design method，introduced several practical protection of circuit.Keywords：switching power supply protection circuit system design1 IntroductionDC switching regulator used in the price of more expensive high—power switching devices, the control circuit is also more complex，In addition，the load switching regulators are generally used a large number of highly integrated devices installed electronic systems. Transistors and integrated device tolerance of electricity, less heat shocks. Thus switching regulator should take into consideration the protection of voltage regulators and load their own safety. Many different types of protection circuits introduced here polarity protection, program protection, over—current protection, over—voltage protection，under voltage protection and thermal protection circuits. Several protection methods are usually chosen to be combined to form a comprehensive protection system。

电力电子技术外文翻译文献(文档含中英文对照即英文原文和中文翻译)译文：基于单片机的开关电源1 用途开关电源产品在工业自动化控制、军工设备、科研设备、LED照明、工控设备、通讯设备、电力设备、仪器仪表、医疗设备、半导体制冷制热、空气净化器，电子冰箱，液晶显示器，LED灯具，通讯设备，视听产品，安防，电脑机箱，数码产品和仪器类等领域中得到广泛应用。

2 简介随着电力电子技术的高速发展，电力电子设备与人们的工作、生活的关系日益密切，而电子设备都离不开可靠的电源，进入80年代计算机电源全面实现了开关电源化，率先完成计算机的电源换代，进入90年代开关电源相继进入各种电子、电器设备领域，程控交换机、通讯、电子检测设备电源、控制设备电源等都已广泛地使用了开关电源，更促进了开关电源技术的迅速发展。

开关电源是利用现代电力电子技术，控制开关晶体管开通和关断的时间比率，维持稳定输出电压的一种电源，开关电源一般由脉冲宽度调制（PWM）控制IC和开关器件（MOSFET、BJT等）构成。

开关电源和线性电源相比，二者的成本都随着输出功率的增加而增长，但二者增长速率各异。

线性电源成本在某一输出功率点上，反而高于开关电源。

随着电力电子技术的发展和创新，使得开关电源技术在不断地创新，这一成本反转点日益向低输出电力端移动，这为开关电源提供了广泛的发展空间。

开关电源高频化是其发展的方向，高频化使开关电源小型化，并使开关电源进入更广泛的应用领域，特别是在高新技术领域的应用，推动了高新技术产品的小型化、轻便化。

另外开关电源的发展与应用在节约能源、节约资源及保护环境方面都具有重要的意义。

3 分类现代开关电源有两种：一种是直流开关电源；另一种是交流开关电源。

这里主要介绍的只是直流开关电源，其功能是将电能质量较差的原生态电源（粗电），如市电电源或蓄电池电源，转换成满足设备要求的质量较高的直流电压（精电）。

直流开关电源的核心是DC/DC转换器。

因此直流开关电源的分类是依赖DC/DC转换器分类的。

Switching Power Supply目录1 Switching Power Supply (1)Linear versus Switching Power Supplies (1)Basic Converters (2)1.2.1Forward-Mode Converter Fundamentals (2)1.2.3 Flyback or Boost-mode Converter Fundamentals (4)1.3 Topologies (5)1 开关电源 (7)1.1 线性电源和开关电源之比拟 (7)根本转换器 (8)1.2.1 前向模式转换器根底 (8)12.2 增压模式转换器根底 (8)1.3 拓扑结构 (9)2 Operational Amplifiers (10)2 放大器 (14)1 Switching Power SupplyEvery new electronic product , except those that battery powered, requires converting off-line 115V ac or 230V ac power to some dc voltage for powering the electronics. Efficient conversion of electrical power is becoming a primary concern to companies and to society as a whole.Switching power supplies offer not only higher efficiencies but also offer greater flexibility to the designer. Recent advances in semiconductor, magnetic and passive technologies make the switching power supply an ever more popular choice in the power conversion arena today.1.1 Linear versus Switching Power SuppliesHistorically, the linear regulator was the primary method of creating a regulated output voltage. It operates by reducing a higher input voltage down to the lower output voltage by linearly controlling the conductivity of a series pass power device in response to changes in its load. This results in a large voltage being placed across the pass unit with the load current flowing through it.This headroom loss ()V I⨯ causes the linear regulator to only be 30 todrop load50 percent efficient. That means that for each watt delivered to the load , at least a watt has to be dissipated in heat. The cost of the heatsink actually makes the linear regulator uneconomical above 10watts for small applications. Below that point, however, they are cost effective in step-down applications.The switching regulator operates the power devices in the full-on and cutoff states. This then results in either large currents being passed through the power devices with a low“on〞voltage or no current flowing with high voltage across the device. This results in a much lower power being dissipated within the supply.The average switching power-supply exhibits efficiencies of between 70 to 90 percent, regardless of the input voltage.Higher levers of integration have driven the cost of switching power supplies downward which makes in an attractive choice for output powers greater than 10 watts or where multiple outputs are desired.1.2 Basic ConvertersForward-Mode Converter FundamentalsThe most elementary forward-mode converter is the Buck or Step-down Converter which can be seen in Figure 3.1.Its operation can be seen as having two distinct time periods which occur when the series power switch is on and off. When the power switch is on ,the inputvoltage is connected to the input of the inductor .The output of switch of inductor is the output voltage, and the rectifier is back-biased. During this period, since there is a constant voltage source connected across the inductor, the inductor current begins to linearly ramp upward which is described by:()()in out on L on V V t i L -⨯=During the “on 〞 period , energy is being stored within the core material of the inductor in the form of flux. There is sufficient energy stored to carry the requirements of the load during the next off period.The next period is the “off 〞 period of the power switch .When the power switch turns off, the input voltage of the inductor flies below ground and is clamped at one diode drop below ground by the catch diode. Current now begins to flow through the catch diode thus maintaining the load current loop. This remove the stored energy from the inductor, The inductor. The inductor current during this time is:()()out D offL off V V t i L -⨯=This period ends when the power switch is once again turned on.Regulation is accomplished by varying the on-to-off duty cycle of the power switch. The relationship which approximately describes its operation is:out in V V ≈∂⨯Where ∂ is the duty cycle (()/on on off t t t ∂=+).The buck converter is capable of kilowatts of output power, but suffers from one serious shortcoming which would occur if the power switch were to fail short-circuited, the input power source is connected directly to the load circuitry with usually produces catastrophic results. To avoid this situation, a crowbar is placed across the output. A crowbar is a latching SCR which is fired when the output is sensed as entering an overvoltage condition. The buckconverter should only be used for board-level regulation.Flyback or Boost-mode Converter FundamentalsThe most elementary flyback-mode converter is the boost or Step-up Converter. Its schematic can be seen in Figure3.2.Its operation can also be broken into two distinct periods where the power switch is on or off. When power switch turns on, the input voltage source is placed directly across the inductor. This causes the current to begin linearly ramping upwards from zero and is described by:()in on L on V t i L ⨯=Once again, energy is being stored during each cycle times the frequency of operation must b higher than the power demands of the load or,20.5sto pkop out P L I f P =⨯⨯>The power switch then turns off and the inductor voltage flies back abovethe input voltage and is clamped and is clamed by the rectifier at the output voltage .The current then begins to linearly ramp downward until the until the energy within the core is completely depleted. Its waveform which is shown in Figure 3.3 is determined by:()()out in offL off V V t i L -⨯=The boost converter should also be only used for board-level regulation.1.3 TopologiesA topology is the arrangement of the power devices and their magnetic elements. Each topology has its own merits within certain applications. Some of the factors which determine the suitability of a particular topology to a certain application are:1) Is the topology electrically isolated from the input to the output or not.2) How much of the input voltage is placed across the inductor or transformer.3) What is the peakcurrent flowing through the power semiconductors.4) Are multiple outputs required.5) How much voltage appears across the power semiconductors.The first choice that faces the designer is whether to have input to output transformer isolation. Non-isolated switching power supplies are typically used for board-level regulation where a dielectric barrier is provided elsewhere within the system. Non-isolated topologies should also be used where the possibility of a failure does not connect the input power source to the fragile load circuitry. Transformer isolation should be used in all other situations. Associated with that is the need for multiple output voltages. Transformers provide an easy method for adding additional output voltage to the switching power supply. The companies building their own power systems are leaning toward transformer isolation in as many power supplies as possible since it prevents a domino effect during failure conditions.1 开关电源除了那些用电池做电源的电子产品外，每个新型电子产品都需要将115V或者230V 的交流电源转换为直流电源，为电路供电。