郑州航空工业管理学院英文翻译2014 届电气工程及其自动化专业班级姓名学号指导教师职称二О一四年 2 月22 日Stepper motorStepper motor is the electrical pulse signal into angular displacement or linear displacement of an open loop stepper motor control element pieces . In the case of non- overloading , motor speed , stopped position depends only on the number of pulse frequency and pulse signals , which are not affected by changes in load , when stepper drive receives a pulse signal , it will drive a stepper motor the rotational direction is set to a fixed angle , referred to as " step angle ", which is fixed to the rotational angle of the step by step operation . The number of pulses can be controlled by controlling the amount of angular displacement , so as to achieve accurate positioning ; while the pulse frequency can be controlled by controlling the motor rotation speed and acceleration to achieve speed control purposes .1. basic introductionStepper motor is an induction motor, it works by using an electronic circuit .The DC power into power -sharing , multi-phase timing control current, this current is powered stepper motor , stepper motor to work properly, the stepper motor drive is powered -sharing , multi-phase timing controller .Although the stepper motor has been widely used, but the stepper motor does not like an ordinary DC motors, AC motors for use in routine under . It must be by a two- ring pulse signal , power driver circuit composed of the control system can be used. So make good use of a stepper motor , but not easy, it involves a lot of expertise in mechanical ,electrical , electronics and computers.Stepper motors as actuators , is one of the key products of mechatronics , widely used in a variety of automated control systems. With the development of microelectronics and computer technology, the growing demand for stepper motor , has applications in various fields of national economy .Stepper motor is an electrical pulse into the angular displacement of the actuator. Plainly speaking : When the stepper drive receives a pulse signal , it will drive a stepper motor to set the direction of rotation of a fixed angle ( ie, step angle . The number of pulses can be controlled by controlling the amount of angular displacement , so as to achieve accurate positioning ; while the pulse frequency can be controlled by controlling the motor rotation speed and acceleration to achieve speed control purposes .2. major categoriesThere are three main types of stepper motors in the structure : Reaction (Variable Reluctance, VR, permanent magnet (Permanent Magnet, PM and hybrid (Hybrid Stepping, HS.Reaction: the stator windings , the rotor soft magnetic material. Simple structure, low cost , small step angle up to 1.2 °, but poor dynamic performance , low efficiency, heat a large , difficult to guarantee reliability .Permanent magnet : permanent magnet stepper motors with permanent magnet rotor material, the number of poles of the rotor and the stator of the same number of poles . Which is characterized by good dynamicperformance, output torque, this motor but poor accuracy , a large step angle (typically 7.5 ° or 15 °.Hybrid : a combination of hybrid stepping motors and permanent magnet reactive advantage of its multi-phase windings on the stator , the rotor permanent magnet material , the rotor and the stator teeth are a number of small steps to improve the accuracy of the moment . It features an output torque, good dynamic performance, step angle is small, but the structure is complex, the cost is relatively high.Press the stator windings to points , a total of two-phase , three-phase and five equal series. Most popular is the two-phase hybrid stepping motor , accounting for more than 97 % market share , the reason is the high cost , coupled with good results after the breakdown of the drive. This kind of basic step angle of the motor 1.8 °/ step , half step back coupled with the drive to reduce the step angle of 0.9 °, coupled with sub-drive after its step angle can be broken up to 256 -fold (0.007 °/ micro step . Due to friction and manufacturing precision and other reasons , the actual control accuracy is slightly lower . Same stepper motors can be equipped with different segments of the drive to change the precision and effectiveness.3. selection methodStepper motor and drive selection methods :Determine how much torque is required : static torque stepper motor is to choose one of the main parameters. Load is large, requires the use of high torque motor. Indicators big moment , the motor appearance is also large.Determine motor speed : high speed requirements , should be selected phase current is larger , smaller inductor motors to increase power input. And select the drive when using higher supply voltages.Select motor installation specifications : as 57,86,110 , the main requirements for the moment .Determine the precision positioning requirements and vibration aspects of the case : to determine whether the required segments, the number of segments required .According to the motor current , supply voltage breakdown and select the drive .4. Basic PrinciplesWorksThe rotor is a permanent magnet motor typically , when a current flows through the stator windings , the stator winding generates a magnetic field vector . The rotating magnetic field to drive the rotor at an angle such that the magnetic field of the stator is consistent with a direction of the magnetic field of the rotor. When the stator magnetic field vector rotation angle. As the rotors turn a field angle . Each input an electrical pulse , the motor rotation angle forward. The number of pulses proportional to the angular displacement of the output and its input , the pulse frequency is proportional to the rotational speed . Change the order of the winding is energized , the motor will reverse. Therefore, the number of pulses can be used to control power-on sequence , frequency and motor windings to control each phase stepper motor rotation .Fever principleUsually see all kinds of motors , are all inside the core and windings . Windings resistance , power will produce loss , the loss is proportional to the square of the size of the resistance and current , and this is what we often say that the copper losses , if thecurrent is not a standard DC or sine wave , but also produce harmonic losses ; core has hysteresis eddy current effect , in the alternating magnetic field will produce losses , its size and materials , current, frequency , voltage dependent , called iron loss. Copper and iron losses are manifested in the form of heat , thus affecting the efficiency of the motor . Stepper motors are generally pursue positioning accuracy and torque output , efficiency is relatively low, the current is generally relatively large, and the high harmonic components , the frequency of the alternating current with the speed of change, thus stepping motor widespread fever cases and situations than the general severe AC motor .5. major tectonicStepping motor is also called a stepper , which uses the principle of electromagnetic , mechanical energy is converted to electrical energy , People as early as the 1920s began to use this motor . As embedded systems ( such as printers, disk drives , toys, wipers, pager vibration , mechanical arm and video recorders , etc. of the increasingly popular use of the stepper motor also began surge. Whether in industrial, military , medical, automotive or entertainment industry , as long as a piece of the object needs to be moved from one location to another , the stepper motor will certainly come in handy. Stepper motors have many shapes and sizes, but regardless of how the shape and size , they can be classified into two categories : a variable reluctance stepper motors and permanent magnetstepper motors.A stepper motor is wound on the motor fixing part - the stator coils driven alveolar . Typically , a ring-shaped metal wire called a solenoid winding , and in the motor , the teeth around the winding wire is called the coil or phase .6. index termsStatic index terms1, number of phases : produce different on pole N, S magnetic excitation coil pairs. Common m said .2, Beats: cyclical changes in the magnetic field required to complete a number of pulses or conductive state with n, or refer to the motor turned a pitch angle required number of pulses to four-phase motor, for example , there are four ways with four -run shot that AB-BC-CD-DA-AB, four-phase eight-shot operation That way A-AB-B-BC-C-CD-D-DA-A. 3, step angle : corresponds to a pulse signal , the angular displacement of the rotor turn is repre sented by θ. θ = 360 degrees / ( number of rotor teeth * run sh ot to the conventional two , four-phase , the rotor teeth 50 teeth motor, for example . Four beats running step angle is θ = 360 degrees / ( 50 * 4 = 1.8 degrees ( commonly known as the full step , eight-shot operation step angle of θ = 360 degrees / ( 50 * 8 = 0.9 degrees ( commonly known as half-step .4, the detent torque : motor is not energized in the state itself locked rotor torque ( harmonics and mechanical error by the magnetic field caused by the tooth .5, static torque : motor at rated static electricity effect, the motor doesnot rotates when the motor shaft locking torque. This moment is a measure of the volume of the standard motor , regardless of the driving voltage and driving power supply. Although static torque is proportional to the electromagnetic excitation ampere-turns , and set the air gap between the rotor teeth related, but over the use of the air gap decreases , increasing the excitation ampere-turns to increase the static torque is not desirable, this will cause motor heating and mechanical noise.Dynamic Indicators term1,step angle accuracy: stepper motor turned every error between the actual value and the theoretical value of a step angle . Expressed as a percentage : error / step angle *100 %. Different running different beats its value , when the four -run shot in the5% ,eight shot should run less than 15 %.2, step : the number of steps the motor running operation does not mean that the theoretical number of steps . Called out of step .3, the offset angle: rotor stator teeth tooth axis shift axis angle , the motor is running there must be offset angle , angle error generated by the imbalance , driven by subdivision can not be solved .4, he maximum no-load starting frequency : motor in the form of a drive voltage and rated current, in the case without the load, the maximum frequency can directly start .5, the operating frequency of the maximum load : the motor in the form of a drive voltage and rated current, the maximum speed of the motor with no load frequency .6, running torque characteristics : Measured motor running undercertain test conditions the output torque versus frequency curve is called the running torque-frequency characteristic , which is the motor of many dynamic curve of the most important , but also the fundamental basis for the motor selection.Other features include inertia frequency characteristics, starting frequency characteristics. Once the motor is selected, the static torque of the motor is determined , and dynamic moment is not the case , the dynamic torque motor depends on the average current ( rather than static current motor is running , the average current , the greater the motor output torque that the motor frequency characteristics of the harder . For the average current, the drive voltage to maximize the use of small high-current inductor motor .7, the resonance point of the motor : stepper motor has a fixed resonance region , two , four-phase Induction resonance zone is generally between 180-250pps ( step angleof 1.8 degrees , or about 400pps ( step angle 0.9 degrees , the higher the motor drive voltage , motor current increases, the lighter the load , motor size smaller, the upward shift resonance region , and vice versa , so that the motor output torque is large , and the entire system without losing step noise reduction , general working point should shift more resonance region .8, motor reversing control : the timing of when the motor windings are energized for the forward , the timing is energized when AB-BC-CD-DA or ( DA-CD-BC-AB or( when inverted.7. features characteristicThe main features1, the general accuracy of the stepper motor step angle of 3-5 % , and does not accumulate.2, the appearance of the stepper motor maximum temperature allowed . First, make a stepper motor temperature magnetic motor demagnetization ,Resulting in the loss of torque down even further , so the maximum temperature of the motor should be allowed depending on the appearance of magnetic motor demagnetization points ; generally speaking, magnetic demagnetization points above 130 degrees Celsius , and some even as high as 200 degrees Celsius above , so the stepper motor surface temperature at 80-90 degrees Celsius completely normal .3, stepper motor torque will increase with the speed of decline .When the stepping motor rotates , the inductance of the motor windings of each phase will form a counter electromotive force ; the higher the frequency, the greater the back EMF . In its role, the motor with frequency ( or speed increases the phase current is reduced , resulting in decreased torque .4, the stepper motor can operate normally at low , but if more than a certain speed will not start , accompanied by howling.Stepper motor has a technical parameter : load starting frequency , ie stepper motor under no-load conditions to start the normal pulse frequency , if the pulse frequency is higher than this value, the motor does not start properly , you may lose steps or stall . Under a load , the starting frequency should be lower . If you want the motor to achieve high-speed rotation , the pulse frequency should speed up the process ,which starts at lower frequencies , and then rise to the hope that at a certain acceleration frequency ( motor speed rise from low speed . Stepper motor with its remarkable features in the era of digital manufacturing plays a significant purpose. Along with improving the different development of digital technology and the technology itself, stepper motor , stepper motors will be applied in more fields .Key FeaturesA stepping motor can be operated must be added before the drive , the drive signal is a pulse signal to be no pulse when the stepping motor is stationary, if the addition of a suitable pulse signal will at a certain angle ( called a step angle is rotated. Rotational speed and the pulse frequency is proportional to .2, phase stepper motor step angle of 7.5 degrees, 360 degrees around , you need to complete the 48 pulses .3, stepper motor with instant start and stop the rapid superior characteristics .4, change the order of the pulse , you can easily change the direction of rotation .Therefore , printers , plotters , robotics and other equipment to the stepper motor driven core .8. speed methodStepper motor pulse signal is converted to angular displacement or linear displacement .First, the overload is good. Its speed independent of load size , unlikeordinary motor when the load increase rate decline occurs when using the stepper motor speed and position , there are stringent requirements.The second is easy to control. Stepper motors are "steps" as a unit rotation , digital features more obvious .Third, the whole structure is simple . Traditional mechanical speed and position control structure is complicated , difficult to adjust after using stepper motors , which makes it simple and compact structure . Motor rotation speed is converted into a voltage , and passed as a feedback signal to the input terminal . Tacho is an auxiliary motor , the motor is installed at the end of the ordinary speed DC motor , the voltage generated by the motor speed feedback to the DC power supply, DC motor speed control to achieve the purpose .9. function module designThis module can be divided into the following three parts:· SCM system : control of stepper motors ;· Peripheral circuits : PIC microcontroller interface circuit and stepper motors ;· PIC procedure : Write SCM stepper electric power machine interface program to achieve output of the triangular wave signal.( 1 stepper motor and microcontroller interface .SCM is the excellent performance of the control processor, stepper motor control , interface components must have the following features.① voltage isolation .SCM work at 5V, while the stepper motor is working in dozens of V, or even higher. Once the voltage to the microcontroller series stepper motor , it will damage the microcontroller ; signals would interfere with chip stepper motor , the system may also lead to errors in the work , so the interface device must have isolation .② messaging functions.Interface components should be able to pass information to the microcontroller stepper motor control circuit generates control information needed work , corresponding to different ways of working, interface components should be able to produce a corresponding job control waveform.③ produce different frequencies required .To the stepping motor at different speeds to suit different purposes , interface components should produce different operating frequencies . ( 2 V oltage Isolation interface.Isolation voltage isolation interface dedicated to the low-pressure part of the microcontroller and the stepper motor drive circuit high-voltage part , to ensure that they work properly.V oltage pulse transformer isolation interface or optical isolator is basically the use of optical isolators. Microcontroller output signal can be sent directly to the TTL gate or base of the transistor , and then driven by the transistor optocoupler devices emitting diodes.Light -emitting diodes on the opto-coupler devices inside the photodiode , converted into electrical signals , go drive a stepper motor power amplifier circuit , current amplification interface is a stepper motoramplifier circuit preamplifier circuit . Its role is to optical isolator output signal current amplification in order to provide enough power amplifier circuit drive current .( 3 Work interface and frequency generator .MCU controlled stepper motor requires the input and output interfaces for controlling stepper motors using three I / 0 lines, this time, the microcontroller I / O port RA0, RAI, RA2 control three-phase stepping motor .10. advantages and defectsAdvantage1, the angle of rotation of the motor is proportional to the number of pulses ;2, when the motor is stopped with a maximum torque ( when winding excitation time ;3, the accuracy of each step in the three percent to five percent , but the error will not accumulate to the next step and thus a better position accuracy and repeatability movement ;4, excellent response from the stop and reverse ;5, since there is no brush , high reliability, and therefore the life of the motor depends only on bearing life ;6, only the response of the motor is determined by the digital input pulse , which can be open-loop control, which makes the structure of the motor can be relatively simple and cost control ;7, only the load can be connected directly to a very low speed synchronous rotation on the shaft of the motor ;8, since the speed is proportional to the pulse frequency , and thus a relatively wide speed range.Defect1, if not properly controlled prone resonance ;2, the high speed operation is difficult ;3, it is difficult to obtain a large torque ;4, there is no advantage, low energy efficiency in terms of volume and weight ;5, more than the load will destroy the synchronization , will be issued when the high speed vibration and noise .11. drive methodStepper motors can be connected directly to the power frequency AC or DC power source to work , but must use a dedicated stepper motor driver , which occurs by the pulse control unit , power drive unit , the protection unit and so on. Stepper motor drive unit with direct coupling , can also be interpreted as a stepper motor controller microprocessor power connector.12. drive requirements1, can provide rapid current rise and fall times ,Current waveform as close as possible to make a rectangle .With a cut-off period for the release of the current flow loop to reducethe back electromotive force at both ends of the windings and accelerate the current decay .2, has a high rhyme power and efficiency.Stepper motor driver , which is a pulse signal into the control system of the angular displacement of the stepper motor , or : a control signal for each pulse issued by the stepper motor drive of a step angle of rotation . That frequency is proportional to the speed of the stepper motor pulse signal. So to control the frequency pulse signal , the speed of the motor can be accurately ; controlled stepper pulse number , you can pinpoint the motor . There are a lot of stepper motor drive , power requirements should be based on the actual reasonable choice drive.13. Major ApplicationsSelect the stepper motorThere are step angle stepping motor ( related to the number of phases , static torque , and the current composition of the three elements .Once identified three elements , the stepper motor model has determined.1, step angle selectionStep motor angle accuracy depends on the load requirements , the minimum resolution of the load ( equivalent conversion to the motor shaft , the number of angles ( including gear for each equivalent motor should go. Step motor angle should be equal to or less than this angle. Step angle stepping motor on the market are generally 0.36 °/0.72 °( five-phase motors , 0.9 degrees / 1.8 degrees ( two , four-phase motor , 1.5 degrees / 3 degrees ( three-phase motors and so on.2, static moment of choiceDynamic torque stepper motor is difficult to determine all of a sudden , we tend to first determine the static torque of the motor. The choice is based on static torque load on the motor work, and the inertia of the load and the load can be divided into two kinds of friction load . Single inertia load and a single load is not present in friction . When direct start ( generally low when the two loads are to be considered , the main consideration inertial load during acceleration start, constant run into just consider friction loads. Under normal circumstances, the static torque should be 2-3 times the load of friction is good, static torque Once selected, the machine base and be able to determine the length of the motor down ( geometry .3, the current selectionLike static torque motors , due to the different current parameters , their operating characteristics vary greatly, can be based on torque-frequency characteristic curve , determine the motor current . Application note points1, the stepper motor used in low-speed situations --- rpm less than 1000 rpm , ( 0.9 degrees 6666PPS, preferably using 1000-3000PPS (0.9 degrees between , can make it work here through deceleration devices, At this high electrical efficiency, low noise ;2, the stepper motor is best not to use the state of the whole step , whole step when the state of vibration ;3, due to historical reasons, only a nominal voltage of 12V 12V motors , the voltage value other than the motor drive voltage V value, drive selectdriving voltage according to ( suggestions : 57BYG DC 24V-36V, 86BYG DC 50V, 110BYG using higher than the DC 80V, of course, in addition to 12 volts 12V constant voltage driver can also use other external power supply, but to consider the temperature rise ;4, the moment of inertia of the load should choose a large frame size motors ;5, when compared with the high-speed motor or high inertia loads , generally do not start working speed , and the use of up- speed gradually , without losing a step motor , two noise can be reduced while improving the positioning accuracy is stopped ;6, high-precision, through mechanical reduction should improve motor speed , or high number of sub-drive to solve, 5 -phase motor can also be used , but the prices of its entire system more expensive , less manufacturer , which is eliminated argument is the layman ;7, the vibration motor in the region should not , should be resolved by changing the voltage , current, or add some damping ;8, motor 600PPS (0.9 degrees following work should be low current , high inductance , low voltage to drive ;9, after the first election should follow the principle of the drive motor option .步进电机步进电机是将电脉冲信号转变为角位移或线位移的开环控制元步进电机件。
