变频器在供水控制系统的应用
目前，在水位控制中有很大一部分水泵电机是不变速拖动系统，不变速电机的电能大多消耗在适应供水量的变化而频繁的开停水泵中。这样不但使电机工作在低效区、减短电机的使用寿命，而且电机的频繁开停使设备故障率很高，导致水资源严重浪费，系统的维护、维修工作量较大。
随着高位生活用水和工业用水逐渐增多，传统的控制方法已经落后。原先用人工进行水位控制，由于无法每时每刻对水位进行准确的定位监测，很难准确控制水泵的起停；使用浮标或机械等水位控制装置使供水状况有了一些改变，但由于机械装置的故障多，可靠性差，给维修带来很大的麻烦。
变频技术以其在节能与恒压方面的优越性能可以解决水压控制系统存在的以上问题。考虑选用单片机或PLC与变频器结合为核心构成的系统都能达到较好的控制效果。但在软件设计上，PLC比单片机的编程更简洁、直观；从硬件接口考虑，单片机电路稍微复杂一些；从经济方面考虑，由于PLC工艺的日渐成熟，小型PLC的成本与单片机相差无几，由于要根据现场情况调整系统参数，PLC的软件中时间参数的调整更简单，这样更有利于售后服务人员掌握。基于以上原因，选用了OMRON的CPM1系列PLC与ABB的变频器作为控制核心，再加上PSW7调节器与WSP300压力变送器，控制效果非常好，软件设计简单，硬件接口简易可行、可靠性高，整个系统的性价比非常高。
在供水系统中引进变频器结合小型PLC技术，不仅改变传统用阀门控制水量多少，而且在节能、恒压控制等方面均有非常好的效果，本文介绍了变频器--PLC调控技术在水泵控制中的应用。
控制系统用一台变频器可以带三台水泵，每台水泵既可以工作在常规工频泵模式，也可以工作在变频泵模式。每台泵只能处于变频或工频其中一种工作模式，通过两个继电器互锁保证它的安全与可靠。系统的结构如图一所示，利用安置在的生活用水中的压力变送器将水的压力信号传输到调节器，根据与调节器的设定值和报警上下限比较，送信号给PLC与变频器，系统的起停泵分别由调节器的压力下限信号和变频器的频率下限信号决定，假如压力低，调节器给PLC一个压力下限信号，PLC启动变频器，并使一号泵处于变频工作状态，输出的频率逐渐增大，经过一段时间的调节，如压力还低，这时，PLC让一号泵处于工频状态工作，使二号泵处于变频工作状态泵，如压力还低，则让二号泵处于工频状态工作，使三号泵处于变频工作状态，如此类推。当压力达到调节器上限报警值时，调节器输出降低，变频器频率降低，低到频率下限设定值，这时变频器给出一个频率下限信号给PLC，PLC根据先启先停的原则控制泵的运行顺序，例如，PLC 收到频率下限信号时，系统中泵的状态是一号工频，二号工频，三号变频，这时一号泵最先启动，所以先停，接着如压力还高，则停二号泵。系统采用了每次都进行低速启动，高速运行以提高运行效率。
采用变频器-PLC恒压供水装置有以下几个优点：
A:节电效益高。传统水泵电机均采用大容量电机，用阀门控制水量恒定，造成电能浪费。
变频系统，无论工作参数如何，电机的效率不会降低，电机的功率因数会得到提高。
B:运行可靠、稳定。系统中的核心部件—变频调速器本身的可靠性很高，一般情况下可连续使用10万/h以上。系统还采用软启动方式，不存在电气冲击，不污染电网，而且变频器自带欠压、过压、过流、过载、过热以及失速等各种保护功能。系统对管网压力波动采取阻尼滤波处理，供水恒压精度较高，通常能控制在0.002Mpa范围内。
C:结构简单，操作简便。装置的控制系统采用集成度高，配套方案灵活多样，由可编程控制器得到水泵运行的各种组合。调速范围广，对水量变化的适应能力强。
D:使用寿命长，自动化程度高，无需人看管，维护量少。
以上系统在实际的应用中效果显著，如将PLC与变频器中自带编程器的功能集成，可开发成一些专用的变频器，这样系统的可靠性与健壮性大大增强，应用更加简单，系统的总成本也会下降。
可以预见：未来的变频技术会向以下方向发展：
(1) 高性能化
包括内部的整流电路、逆变电路都采用高频PWM电路从而使输入、输出都是正弦波；对于大容量变频器采用多重化和多机并联；降低变频器自身损耗，实现高效率化；实现自动调谐或自优化、遥控和远控；更加面向用户，进一步提高可使用性和维修性：向着小型、轻量发展，以及降低成本等。
(2) 智能化
包括两个方面：尽量减少硬件，实现硬件软件化；采用智能电力电子器件和其他智能化部件。集成化是智能化的基础。
(3) 全数字化
近年来，各种现代控制理论、专家系统、模糊控制及神经元控制等都是发展的热点，将使电力电子控制技术发展到一个崭新的阶段。预计21世纪全数字控制的应用将更加广泛深入，甚至取代模拟控制。
(4) 系统化
变频技术的发展与其相关技术的发展是分不开的，在21世纪变频技术的发展是将电网、整流器、逆变器、电动机、生产机械和控制系统等作为一个整体、从系统上进行考虑的。
Transducer in the water control system applications
Currently, the water level control in a large part of the electrical pumps are not towing gear shift system, no gear shift most of the electrical energy consumed in the water supply to the frequent changes in the pumps stopped. This not only makes the electrical work in inefficient zones, cut short the useful life of electrical and electrical equipment for the frequent failure to stop the high rate, leading to serious waste of water resources, system maintenance, repairs larger workload.
With high living water and industrial water gradually increased, the traditional control methods that are outdated. Originally used for artificial water level control, water level due to the lack of accurate positioning hour monitoring, it is difficult to accurately control the pumps have stopped; Using buoys or mechanical control devices such as water supply situation has made some changes, but because of mechanical failure more devices, poor reliability to maintenance will face great trouble.
Frequency conversion technology, with its superiority in the area of energy efficiency and Hengya pressure control system can be solved by the existence of the above problems. Consider selecting Chanpianji or Plc and transducer combination at the core of the system can achieve a better control results. But in software design, Plc programming of more than Shanpianji concise, and visual; From the hardware interface considerations, Shanpianji circuit slightly complex; From the economic considerations, the Plc processes are mature, cost and small Plc Shanpianji a little, because the system parameters to be adjusted in accordance with the situation on the ground, Plc software, the time parameters adjustments simpler, so more conducive to after-sale personnel. For the above reasons, the selection of the Omron Plc CPM1 series with the transducer as ABB control core, coupled with PSW7 conditioners and WSP300 Biansongqi pressure, the effect was very good control, software design simple hardware interface simple and feasible, reliable, the entire system Xingjiebi very high.
Transducer in the water system in conjunction with the introduction of small Plc technology not only change the traditional use of water control valves, and in energy conservation, Hengya control, are very good results, the paper introduced a transducer --PLC control technology in the pump control applications.
Control system using one Taiwan transducer can bring three pumps, pumps can work at the frequency pump in the conventional model can work in the frequency conversion pump model. At the pump only in frequency conversion or one of the working frequency mode through two relays efficient ensure its security and reliability.
System structure as figure 1 shows, the use of placement in the life of water pressure Biansongqi water pressure signal transmission to the regulator, in accordance with the regulator to set the value and warning of lower compared to send signals to the Plc and the transducer, the system has stopped pumping from regulator pressure level signals and transducer frequency range signal, if the low pressure, regulator to the Plc a pressure lower signal Plc activation transducer, and a frequency conversion 1st pumps work state, and the output frequency gradually increasing, after a period of adjustment, such as pressure is low, then, Plc for 1st pumps in the frequency of work, 2nd pump frequency conversion work at the state pumps, such as pressure is low, 2 pumps at the frequency for the state and make the state 3rd pumps in frequency conversion work, and so on. When the pressure regulator to limit the police on duty, regulator output reduction, transducer frequency reduced to the low frequency range set value at a given frequency transducer signals to the lower PLC,PLC According to Kai principle pause control pump operation sequence, for example, Plc received lower frequency signals, the system pumps state is the frequency 1st, 2nd-frequency, 3rd frequency conversion, the first time 1st pumps activated, the first stop, then as the pressure was high, then stopped on the 2nd pumps. Each system is used for slow start, high-speed operation in order to enhance operational efficiency.
Introduces the frequency changer union small PLC technology in the water supply system, not only change tradition with valve control water volume how many, moreover in aspects and so on energy conservation, constant pressure control had the extremely good effect, this article introduced the frequency changer--PLC regulation technology in water pump control application.
The control system may bring three water pumps with a frequency changer, each water pump already may work in the conventional power frequency pump pattern, also may work in the frequency conversion pump pattern. Each pump only can be in the frequency conversion or the power frequency one kind of working pattern, guarantees its safety and the unreliability mutually through two relay locks. System structure as shown in Figure one, the use places in the domestic water pressure transmitting instrument the water pressure signaling regulator, and reports to the police the bound according to and the regulator setting value to compare, delivers a letter the number for PLC and the frequency changer, the system stops the pump separately decided by the regulator low pressure limit signal and the frequency changer lower frequency limit signal, if the pressure is low, the regulator for a PLC low pressure limit signal, the PLC start frequency changer, and causes the first pump to be at the frequency conversion active status, the output frequency increases gradually, passes through a period of time adjustment, if the pressure is also low, by now, PLC let the first pump be at the power frequency conditionThe work, causes the
second pump to be at the frequency conversion active status pump, if the pressure is also low, then lets the second pump be at the power frequency condition work, causes the third pump to be at the frequency conversion active status, so analogizes. When the pressure achieved when the regulator upper limit reported to the police the value, the regulator outputs reduces, the frequency changer frequency reduces, lowers to the lower frequency limit setting value, by now the frequency changer gave a lower frequency limit signal the principle which opened first for the PLC, PLC basis stops first to control the pump the movement order, when for example, PLC received the lower frequency limit signal, in the system the pump condition was a power frequency, two power frequencies, three frequency conversion, the first pump first started by now, therefore stopped first, like the pressure also was then high then stopped the second pump. The system used all has each time carried on the low speed to start, the high speed movement enhanced the operating efficiency.
Uses the frequency changer - PLC constant pressure water supply installment to have following several merits:
A:The electricity saving benefit is high. The traditional water pump electrical machinery uses the large capacity electrical machinery, is constant with the valve control water volume, creates the electrical energy waste.
Frequency conversion system, regardless of the operational parameter how, the electrical machinery efficiency can't reduce, the electrical machinery power factor can obtain the enhancement.
B:Moves is reliable, is stable. In the system core part - frequency conversion velometer itself reliability is very high, in the ordinary circumstances may the long-term usage 100,000/Above h. The system also selects the soft start method, does not have the electrical impact, does not pollute the electrical network, moreover frequency changer bringing owes presses, the pressure, the overflow, the overload, superheat as well as loses speed and so on each kind of protection function. The system adopts damping filter processing to the pipe network fluctuation of pressure, the water supply constant pressure precision is high, usually can control in the 0.002Mpa scope.
C:The structure is simple, the operation is simple. The installment control system uses the integration rate to be high, necessary plan nimble diverse, obtains water pump movement each kind of combination by the programmable controller. The velocity modulation scope is broad, to water volume change adaptiveness.
D:The service life is long, the automaticity is high, does not need the human to safeguard, maintains the quantity to be few.
Above system the effect is remarkable in the actual application, if brings in PLC and the frequency changer the programmer the function integration, potential
becomes some special-purpose frequency changers, such system reliability and the toughness big enhancement, the application is simpler, the system total cost also can drop.
May foresee: The future frequency conversion technology will be able to develop to the below direction:
(1) high performance
Thus including internal leveling circuit, the contravariant electric circuit all use the high frequency PWM electric circuit to cause the input, the output all are sine waves; Uses the multi-densification regarding the large capacity frequency changer and many machine is parallel; Reduces frequency changer own loss, the realization high efficiency; Realizes autotune or from the optimization, the remote control and controls far; Even more faces the user, further enhances the workability and Maintainability: Turns towards, the featherweight development small, as well as reduces the cost and so on.
(2) intellectualization
Including two aspects: Reduces the hardware as far as possible, realizes the hardware software; Uses the intelligent electric power electronic device and other intellectualized part. The integration is the intellectualized foundation.
(3) entire digitization
In recent years, each kind of modern control theory, the expert system, the fuzzy control and the neuron control and so on all were the development hot spots, will cause the electric power electronic control technological development to a brand-new stage. Estimated the 21st century entire numerical control the application will be more widespread thoroughly, even will substitute for the simulation control.
(4) systematization
Frequency conversion technology development is inseparable from the development of related technologies, frequency conversion technology development in the 21st century is to grid, regulators, rely machine, electric motors, production machinery and control systems as a whole, from the system for consideration.
中英文对照资料外文翻译文献 附件1：外文资料翻译译文 传感器新技术的发展 传感器是一种能将物理量、化学量、生物量等转换成电信号的器件。输出信号有不同形式，如电压、电流、频率、脉冲等，能满足信息传输、处理、记录、显示、控制要求，是自动检测系统和自动控制系统中不可缺少的元件。如果把计算机比作大脑，那么传感器则相当于五官，传感器能正确感受被测量并转换成相应输出量，对系统的质量起决定性作用。自动化程度越高，系统对传感器要求越高。在今天的信息时代里，信息产业包括信息采集、传输、处理三部分，即传感技术、通信技术、计算机技术。现代的计算机技术和通信技术由于超大规模集成电路的飞速发展，而已经充分发达后，不仅对传感器的精度、可靠性、响应速度、获取的信息量要求越来越高，还要求其成本低廉且使用方便。显然传统传感器因功能、特性、体积、成本等已难以满足而逐渐被淘汰。世界许多发达国家都在加快对传感器新技术的研究与开发，并且都已取得极大的突破。如今传感器新技术的发展，主要有以下几个方面： 利用物理现象、化学反应、生物效应作为传感器原理，所以研究发现新现象与新效应是传感器技术发展的重要工作，是研究开发新型传感器的基础。日本夏普公司利用超导技术研制成功高温超导磁性传感器，是传感器技术的重大突破，其灵敏度高，仅次于超导量子干涉器件。它的制造工艺远比超导量子干涉器件简单。可用于磁成像技术，有广泛推广价值。 利用抗体和抗原在电极表面上相遇复合时，会引起电极电位的变化，利用这一现象可制出免疫传感器。用这种抗体制成的免疫传感器可对某生物体内是否有这种抗原作检查。如用肝炎病毒抗体可检查某人是否患有肝炎，起到快速、准确作用。美国加州大学巳研制出这类传感器。 传感器材料是传感器技术的重要基础，由于材料科学进步，人们可制造出各种新型传感器。例如用高分子聚合物薄膜制成温度传感器；光导纤维能制成压力、流量、温度、位移等多种传感器；用陶瓷制成压力传感器。
变频器外文翻译文献 (文档含中英文对照即英文原文和中文翻译)
外文: Converter reference design (1)Converter Selection: Selection to determine the frequency converter when the following points: 1) The purpose of a variable frequency; constant pressure to control or constant current control. 2) the load converter types such as leaves or pump volume pumps, with special attention to load the performance curve, the performance curve of the decision of the ways and means. 3) the frequency converter and load matching Voltage match: a rated voltage converter with a rated voltage line with the load. Current matches: ordinary pump, the rated current inverter and motor rated current match. For special load such as deep-water pumps, and so on need to refer to the electrical performance parameters to determine the most current inverter current and Guozainengli. Torque match: in this case constant torque load or slow down when the device may have occurred. 4) the use of high-speed motor drive inverter, because of the high-speed motor, anti-small, high harmonics lead to increased output current value increases. So for high-speed motor inverter Selection, its capacity to be slightly larger than the ordinary motor selection. 5) If the frequency converter to a long cable run, this time to take measures to curb the long cable to the impact of capacitive coupling, inadequate efforts to avoid converter, so in this case, the drive to enlarge the capacity of a file or the converter Output installed output reactor. 6) For the application of some special occasions, such as high temperatures, high altitude, at this time would cause the down converter capacity, the drive to enlarge the capacity of a block.
forced concrete structure reinforced with an overviewRein Since the reform and opening up, with the national economy's rapid and sustained development of a reinforced concrete structure built, reinforced with the development of technology has been great. Therefore, to promote the use of advanced technology reinforced connecting to improve project quality and speed up the pace of construction, improve labor productivity, reduce costs, and is of great significance. Reinforced steel bars connecting technologies can be divided into two broad categories linking welding machinery and steel. There are six types of welding steel welding methods, and some apply to the prefabricated plant, and some apply to the construction site, some of both apply. There are three types of machinery commonly used reinforcement linking method primarily applicable to the construction site. Ways has its own characteristics and different application, and in the continuous development and improvement. In actual production, should be based on specific conditions of work, working environment and technical requirements, the choice of suitable methods to achieve the best overall efficiency. 1、steel mechanical link 1.1 radial squeeze link Will be a steel sleeve in two sets to the highly-reinforced Department with superhigh pressure hydraulic equipment (squeeze tongs) along steel sleeve radial squeeze steel casing, in squeezing out tongs squeeze pressure role of a steel sleeve plasticity deformation closely integrated with reinforced through reinforced steel sleeve and Wang Liang's Position will be two solid steel bars linked Characteristic: Connect intensity to be high, performance reliable, can bear high stress draw and pigeonhole the load and tired load repeatedly.
中英文资料对照外文翻译 基于网络共享的无线传感网络设计 摘要：无线传感器网络是近年来的一种新兴发展技术，它在环境监测、农业和公众健康等方面有着广泛的应用。在发展中国家，无线传感器网络技术是一种常用的技术模型。由于无线传感网络的在线监测和高效率的网络传送，使其具有很大的发展前景，然而无线传感网络的发展仍然面临着很大的挑战。其主要挑战包括传感器的可携性、快速性。我们首先讨论了传感器网络的可行性然后描述在解决各种技术性挑战时传感器应产生的便携性。我们还讨论了关于孟加拉国和加利 尼亚州基于无线传感网络的水质的开发和监测。 关键词：无线传感网络、在线监测 1.简介 无线传感器网络，是计算机设备和传感器之间的桥梁，在公共卫生、环境和农业等领域发挥着巨大的作用。一个单一的设备应该有一个处理器，一个无线电和多个传感器。当这些设备在一个领域部署时，传感装置测量这一领域的特殊环境。然后将监测到的数据通过无线电进行传输，再由计算机进行数据分析。这样，无线传感器网络可以对环境中各种变化进行详细的观察。无线传感器网络是能够测量各种现象如在水中的污染物含量，水灌溉流量。比如，最近发生的污染涌流进中国松花江，而松花江又是饮用水的主要来源。通过测定水流量和速度，通过传感器对江水进行实时监测，就能够确定污染桶的数量和流动方向。 不幸的是，人们只是在资源相对丰富这个条件下做文章，无线传感器网络的潜力在很大程度上仍未开发，费用对无线传感器网络是几个主要障碍之一，阻止了其更广阔的发展前景。许多无线传感器网络组件正在趋于便宜化（例如有关计算能力的组件），而传感器本身仍是最昂贵的。正如在在文献[5]中所指出的，成功的技术依赖于
Programmable logic controller A programmable logic controller (PLC) or programmable controller is a digital computer used for automation of electromechanical processes, such as control of machinery on factory assembly lines, amusement rides, or lighting fixtures. PLCs are used in many industries and machines. Unlike general-purpose computers, the PLC is designed for multiple inputs and output arrangements, extended temperature ranges, immunity to electrical noise, and resistance to vibration and impact. Programs to control machine operation are typically stored in battery-backed or non-volatile memory. A PLC is an example of a real time system since output results must be produced in response to input conditions within a bounded time, otherwise unintended operation will result. 1.History The PLC was invented in response to the needs of the American automotive manufacturing industry. Programmable logic controllers were initially adopted by the automotive industry where software revision replaced the re-wiring of hard-wired control panels when production models changed. Before the PLC, control, sequencing, and safety interlock logic for manufacturing automobiles was accomplished using hundreds or thousands of relays, cam timers, and drum sequencers and dedicated closed-loop controllers. The process for updating such facilities for the yearly model change-over was very time consuming and expensive, as electricians needed to individually rewire each and every relay. In 1968 GM Hydramatic (the automatic transmission division of General Motors) issued a request for proposal for an electronic replacement for hard-wired relay systems. The winning proposal came from Bedford Associates of Bedford, Massachusetts. The first PLC, designated the 084 because it was Bedford Associates' eighty-fourth project, was the result. Bedford Associates started a new company dedicated to developing, manufacturing, selling, and servicing this new product: Modicon, which stood for MOdular DIgital CONtroller. One of the people who worked on that project was Dick Morley, who is considered to be the "father" of the PLC. The Modicon brand was sold in 1977 to Gould Electronics, and later acquired by German Company AEG and then by French Schneider Electric, the current owner. One of the very first 084 models built is now on display at Modicon's headquarters in North Andover, Massachusetts. It was presented to Modicon by GM, when the unit was retired after nearly twenty years of uninterrupted service. Modicon used the 84
Constant pressure water supply frequency changer The transistor frequency changer not only overcame has formerly exchanged velocity modulation many shortcomings, moreover the velocity modulation performance might compare favorably with the direct current motor velocity modulation performance. The three-phase asynchronous motor has the service to be convenient, merit and so on price small advantage, power and rotational speed adapt breadth, its frequency conversion velocity modulation technology in the miniaturization, the low cost and the redundant reliable aspect holds the obvious superiority. To the end of the 80's, the alternating current machine frequency conversion velocity modulation technology rapidly develops into a mature technology, it will supply the alternating current machine the labor frequency alternating current supply to turn direct current after the diode rectification, again by component and so on IGBT or GTR module counter will turn the alternating current supply which the frequency might move, will drive the electrical machinery by this power source to move under the speed change condition, and automatic suitable strain load condition. After it changed in the traditional industry the electrical machinery to start only can by the rated power, decide the rotational speed the sole movement way, thus achieved the energy conservation goal. The modern frequency conversion velocity modulation technology applies in the electric power water pump water supply system. Because the frequency conversion velocity modulation has the velocity modula -tion the physical characteristics well, efficiency high, velocity modulation scope -wide, precision high, adjusting character curve smooth, may continual realize, the steady velocity modulation, the volume small, the maintenance simple is conven -ient, the automated level higher a series of prominent merits but time people's favor. When it applies especially in the air blower, the water pump and so on the large capacity load, may obtain the energy conservation effect which other velocity modulation ways is unable to compare. The frequency conversion velocity modulation system main equipment is provides the frequency conversion power source the frequency changer, the frequency changer may divide into exchange - direct current - to exchange the frequency changer and the exchange - exchan
Study on Project Cost Control of Construction Enterprises By: R. Max Wideman Abstract With the increasing maturity of construction market, the competition between construction enterprises is becoming fierce. The project profit is gradually decreasing. It demands that all construction enterprises enhance their cost control, lower costs, improve management efficiency and gain maximal profits. This paper analyses the existing problems on project cost control of Chinese construction enterprises, and proposes some suggestions to improve project cost control system. Key Words ：Construction enterprises, Project management, Cost control After joining the WTO, with Chinese construction market becoming integrated, the competition among architectural enterprises is turning more intense. Construction enterprises must continually enhance the overall competitiveness if they want to develop further at home and abroad construction market. Construction Enterprises basically adopt the "project management-centered" model, therefore, it is particularly important to strengthen project cost control. 1.The Current Domestic Project Cost Classification and Control Methods Cost refers to the consumption from producing and selling of certain products, with the performance of various monetary standing for materialized labor and labor-consuming. Direct and indirect costs constitute the total cost, also known as production cost or manufacturing cost. Enterprise product cost is the comprehensive indicator to measure enterprise quality of all aspects. It is not only the fund compensation scale, but also the basis to examine the implementation of cost plan. Besides, it can provide reference for product pricing According to the above-mentioned definition and current domestic cost classification, construction project cost can be divided into direct costs and indirect costs. Direct costs include material cost, personnel cost, construction machinery cost, material transportation cost, temporarily facility cost, engineering cost and other direct cost. Indirect costs mainly result from project management and company's cost-sharing, covering project operating costs (covering the commission of foreign projects), project's management costs (including exchange losses of
压力传感器 合理进行压力传感器的误差补偿是其应用的关键。压力传感器主要有偏移量误差、灵敏度误差、线性误差和滞后误差，本文将介绍这四种误差产生的机理和对测试结果的影响，同时将介绍为提高测量精度的压力标定方法以及应用实例。 目前市场上传感器种类丰富多样，这使得设计工程师可以选择系统所需的压力传感器。这些传感器既包括最基本的变换器，也包括更为复杂的带有片上电路的高集成度传感器。由于存在这些差异，设计工程师必须尽可能够补偿压力传感器的测量误差，这是保证传感器满足设计和应用要求的重要步骤。在某些情况下，补偿还能提高传感器在应用中的整体性能。 本文以摩托罗拉公司的压力传感器为例，所涉及的概念适用于各种压力传感器的设计应用。 摩托罗拉公司生产的主流压力传感器是一种单片压阻器件，该器件具有 3 类： 1.基本的或未加补偿标定； 2.有标定并进行温度补偿； 3.有标定、补偿和放大。 偏移量、范围标定以及温度补偿均可以通过薄膜电阻网络实现，这种薄膜电阻网络在封装过程中采用激光修正。 该传感器通常与微控制器结合使用，而微控制器的嵌入软件本身建立了传感器数学模型。微控制器读取了输出电压后，通过模数转换器的变换，该模型可以将电压量转换为压力测量值。传感器最简单的数学模型即为传递函数。该模型可在整个标定过程中进行优化，并且模型的成熟度将随标定点的增加而增加。 从计量学的角度看，测量误差具有相当严格的定义：它表征了测量压力与实际压力之间的差异。而通常无法直接得到实际压力，但可以通过采用适当的压力标准加以估计，计量人员通常采用那些精度比被测设备高出至少 10 倍的仪器作为测量标准。 由于未经标定的系统只能使用典型的灵敏度和偏移值将输出电压转换为压 力，测得的压力将产生如图 1 所示的误差。 这种未经标定的初始误差由以下几个部分组成： a.偏移量误差。由于在整个压力范围内垂直偏移保持恒定，因此变换器扩散和激光调节修正的变化将产生偏移量误差。 b.灵敏度误差，产生误差大小与压力成正比。如果设备的灵敏度高于典型值，灵敏度误差将是压力的递增函数（见图 1）。如果灵敏度低于典型值，那么灵敏度误差将是压力的递减函数。该误差的产生原因在于扩散过程的变化。
毕业设计--基于PLC的变频调速恒压供水系统（含外文翻 译） 山东科技大学学士学位论文摘要 摘要 本论文根据中国城市小区的供水要求，设计了一套基于PLC的变频调速恒压供水系统, 并利用组态软件开发良好的运行管理界面。变频恒压供水系统由可编程控制器、变频器、水泵机组、压力传感器、工控机等构成。 本系统包含三台水泵电机，它们组成变频循环运行方式。采用变频器实现对三相水泵电机的软启动和变频调速，运行切换采用“先启先停”的原则。压力传感器检测当前水压信号，送入PLC与设定值比较后进行PID运算，从而控制变频器的输出电压和频率，进而改变水泵电机的转速来改变供水量，最终保持管网压力稳定在设定值附近。通过工控机与PLC的连接，采用组态软件完成系统监控，实现了运行状态动态显示及数据、报警的查询。 关键词:变频调速，恒压供水，PLC，组态软件 山东科技大学学士学位论文 ABSTRACT ABSTRACT According to the requirement of China's urban water supply, this paper designs a set of water supply system of frequecey control of constant voltage based on PLC, and have developed good operation management interface using Supervision Control and Data Acquisition.The system is made up of PLC, transducer,units of pumps,pressure sensor and control machine and so on.
（ 二 〇 一 二 年 六 月 外文文献及翻译 题 目： About Buiding on the Structure Design 学生姓名： 学 院：土木工程学院 系 别：建筑工程系 专 业：土木工程(建筑工程方向) 班 级：土木08-4班 指导教师：
英文原文： Building construction concrete crack of prevention and processing Abstract The crack problem of concrete is a widespread existence but again difficult in solve of engineering actual problem, this text carried on a study analysis to a little bit familiar crack problem in the concrete engineering, and aim at concrete the circumstance put forward some prevention, processing measure. Keyword:Concrete crack prevention processing Foreword Concrete's ising 1 kind is anticipate by the freestone bone, cement, water and other mixture but formation of the in addition material of quality brittleness not and all material.Because the concrete construction transform with oneself, control etc. a series problem, harden model of in the concrete existence numerous tiny hole, spirit cave and tiny crack, is exactly because these beginning start blemish of existence just make the concrete present one some not and all the characteristic of quality.The tiny crack is a kind of harmless crack and accept concrete heavy, defend Shen and a little bit other use function not a creation to endanger.But after the concrete be subjected to lotus carry, difference in temperature etc. function, tiny crack would continuously of expand with connect, end formation we can see without the
Basic knowledge of transducers A transducer is a device which converts the quantity being measured into an optical, mechanical, or-more commonly-electrical signal. The energy-conversion process that takes place is referred to as transduction. Transducers are classified according to the transduction principle involved and the form of the measured. Thus a resistance transducer for measuring displacement is classified as a resistance displacement transducer. Other classification examples are pressure bellows, force diaphragm, pressure flapper-nozzle, and so on. 1、Transducer Elements Although there are exception ,most transducers consist of a sensing element and a conversion or control element. For example, diaphragms,bellows,strain tubes and rings, bourdon tubes, and cantilevers are sensing elements which respond to changes in pressure or force and convert these physical quantities into a displacement. This displacement may then be used to change an electrical parameter such as voltage, resistance, capacitance, or inductance. Such combination of mechanical and electrical elements form electromechanical transducing devices or transducers. Similar combination can be made for other energy input such as thermal. Photo, magnetic and chemical,giving thermoelectric, photoelectric,electromaanetic, and electrochemical transducers respectively. 2、Transducer Sensitivity The relationship between the measured and the transducer output signal is usually obtained by calibration tests and is referred to as the transducer sensitivity K1= output-signal increment / measured increment . In practice, the transducer sensitivity is usually known, and, by measuring the output signal, the input quantity is determined from input= output-signal increment / K1. 3、Characteristics of an Ideal Transducer The high transducer should exhibit the following characteristics a) high fidelity-the transducer output waveform shape be a faithful reproduction of the measured; there should be minimum distortion. b) There should be minimum interference with the quantity being measured; the presence of the transducer should not alter the measured in any way. c) Size. The transducer must be capable of being placed exactly where it is needed.
毕业论文（设计）外文翻译 题目：可编程逻辑控制器技术 系部名称：信息工程系专业班级： 学生姓名：学号： 指导教师：教师职称： 2014 年3 月XX 日
译文 可编程逻辑控制器技术 引言 PLC（可编程逻辑控制器）实际是一个工业控制系统（近来我们看到更多的是用处理器来取代微控制器），在软件和硬件都配备的条件下，适合应用于工业环境。PLC 的发明是相当必要的，它代替了传统的依靠由继电接触器电路来控制电机。PLC 的工作原理是根据它的输入信号和工作状态来确定输出。用户通常是通过软件或编程输入一个程序，来输出所需要的结果。 如图 8-1 所示，PLC 是由典型的黑色构件组成。特别需要注意的是它的输入和输出， 因为在这些模块上，工业环境会给 CPU 一个输入线，所以很有必要将 CPU 模块隔离以保护其免遭有害的影响。程序单元通常是用计算机来编写程序（一般是梯形图）。 1.1CPU 的中央处理单元 中央处理单元（CPU）是一个 PLC 的主控制器。一般 CPU 本身是一个微控制器。通常这些都是 8 位微控制器，如 8051 ，现在的这些是 16 位和 32 位微控制器。潜规则是，你会发现用在 PLC 控制器上的微控制器多数是由日本生产的日立和富士通，欧洲的西门子控制器，和美国的摩托罗拉微控制器。CPU 也负责通讯，与 PLC 控制器的其它部分相互联系，如程序执行，内存操作，监督输入和设置输出。PLC 控制器拥有复杂的程序用于内存检查，以确保 PLC 内存不被损坏（内存检查是为了安全原因而作出的）。一般来说，CPU 单元多数用来检查 PLC 控制器本身，所以有可能出现的错误很早就会被发现。你可以简单地看任何 PLC 控制器,查看错误信号在发光二极管上的种种指示形式。 1.2内存 系统内存（今天主要是在 FLASH 技术上实现）用于一台 PLC 的过程控制系统。除了 这个操作系统它还包含用户程序将梯形图翻译成二进制的形式。 FLASH 存储器的内容仅在 用户程序改变下可以改变。PLC 控制器较早被用来代替闪存，EPROM 存储器代替了那些只能依靠紫外线灯等擦除内存并依靠程序员来编程的 FLASH 存储器。在 FLASH 技术的作用下这个过程被大大的缩短了。重组程序内存通过程序中的串行通讯用于应用程序开发。使用内存被划分成多个具有特殊功能的模块。存储器某些部分用来存储输入状态和输出状态。一个 输入信号的实际状态是用 1 或0 存储在一个特定的存储位。每一个输入信号和输出信号在内存里都有一个位与之相对应。内存的其他部分用来存储用户程序中使用的变量以及变量的内容。例如，定时器的值和计数器的值都将被存储在这部分内存里。 1.3PLC 控制器的编程 PLC 控制器可以通过计算机（常用的方式）进行编程，还可以通过手动编程器（控制台）编程。这实际上意味着如果你有需要的编程软件那么每个 PLC 控制器都可以通过计算机进行编程。今天的传输计算机是非常适合在工厂对 PLC 控制器进行编程的。这对工业有着非常重要的意义。一旦系统被刷新，重新读取正确的程序到 PLC 就很重要。还可以定期检查 PLC 中的程序是否改变了。这有助于避免在工厂车间发生危险状况（部分汽车制造商建立了通信网络，定期检查项目中的 PLC 控制器，以确保执行的程序是正确的）。