PLC 和PID 简介毕业论文外文翻译.docx

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1、1PLC 和PID 简介可编程控制器(PLC) 作为一种新型的工业控制装置, 在科研、生产、社会生活等诸多领域得到了越来越广泛的应用。它具备可塑性、可记忆性、可接受多种方式的输入/输出等优点, 除了单独一台的控制之外, 更可进行多台的连接, 控制功能强大易于达成整体自动化的目标, 尤其是具有可更改性, 可重复使用,非常值得推广, 因此已广受自动控制界的欢迎。PLC作为一种很有特色和发展前途的控制设备, 目前主要用于有大量开关量和少数模拟量的控制系统中。在工业生产过程控制中, 模拟量的P ID (比例、积分、微分) 调节是常见的一种控制方式, 这是由于P ID调节不需要求出控制系统的数学模型。同

2、时P ID 调节器又具有典型的结构, 可以根据被控对象的具体情况,采用P ID 的变种, 有较强的灵活性和适用性。一般中小型PLC 控制系统只对一路或几路模拟量进行闭环控制, 硬件上只需配备A /D 及D/A 转换模块, 软件可购买相应厂家提供的P ID 编程功能模块, 只需设定好P ID 参数, 运行P ID 控制指令, 就能准确控制回路的输出值。2问题的提出及实验方案近零的水平温控系统是典型的工业控制对象, 被广泛应用于工业生产领域中的各个行业, 甚至在日常生活中温控系统也十分常见。温控系统控制方法的优劣、运行效果的好坏, 直接影响到产品的质量、能源的消耗以及设备的生产效率。温控系统的被控

3、对象往往是比较复杂的, 具有大惯性、纯后、参数时变等特征。本文以A - B 系列PLC M icro logix1500 和模拟量输入/输出模块1771- IFE、1771- O FE 作为温控系统的主要元件, 驱动加热元件以达到我们所需求的控制值。目前采用的常规P ID 控制在实际生产现场中受到参数整定方法繁杂的困扰, 参数往往整定不良、性能欠佳。针对这些问题, 我们采用了罗克韦尔RSTuneP ID 参数协调软件, 并应用到本系统来调节P ID 参数。在P ID 控制器中, 误差信号(受控系统期望的温度与实际温度之间的差值) 在加到温度控制电源驱动电路之前先分别以三种方式( 比例、积分和微

4、分) 被放大。比例增益向误差信号提供瞬时响应; 积分增益求出误差信号的积分, 并将误差减低到接, 积分增益还有助于过滤掉实测温度信号中的噪音; 微分增益使驱动依赖于实测温度的变化率。在许多情况下，比例积分控制策略也可以产生满足要求的结果, 而且通常要比完全的PID 控制器更容易调整到稳定的运行状态, 并获得符合要求的稳定时间。3温控系统设计A - B 系列的PLC 和模拟量输入/输出单元Micro logix1500 是A - B 公司生产的一种功能强大的微型可编程序控制器, 它采用新颖的两块式组合结构, 具有可扩展Compact I/O 、内置P ID、实时时钟RTC 功能和两路20kHz

5、高速计数器, 它还内置2 路模拟量微调电位器。输入单元1771- IFE 是一块智能的块传送模块, 它将模拟量输入信号传送至任何具有传送能力的A - B PLC 接口, 并将模拟量(如温度、压力) 转换成一个成比例的12 位二进制数或一个4 位BCD 值, 转换后的值存储在模块的存储器中, 通过块传送指令发送到PLC。每个模块可以组态最多16 路单端输入或8 路差动输入。输出模块1771- O FE 具有4 个输出通道, 在每一个通道上可将二进制或4 位BCD 码转换成模拟量信号, 以驱动相应的输出设备。控制系统设计原理电加热炉的温控系统主要由加热元件、加热设备、绝缘材料、功率调节器和温度传感

6、器(热电偶) 元件等组成。其温度控制系统见图1。 图1 温度控制系统框图通过调节双向可控硅的通断来调节电炉丝的输出功率, 由温度检测元件热电偶将采集到的炉膛温度信号通过模数转换, 变成数字量传给PLC。用编制好的程序对其进行计算, 得到实际温度值, 再与给定的温度值相比较, 得到的偏差值经过P ID 运算后, 输出的数字量经过数模转换, 再由输出模块送给可控硅电压调整器, 产生可控硅脉冲触发信号, 该信号触发可控硅电路, 最终由该电路驱动电炉的加热丝。通过调整可控硅触发信号(即调节供电电压每个周期的导通角),即可控制电炉电压的通断及大小, 进而达到控制炉温的目的。附录21 PLC and PI

7、D profile Programmable controller (PLC) is used as a new industrial control device, in scientific research, production and social life and so on many domains have been applied more and more. It has plasticity, memory sex, acceptable various ways of input/output etc, in addition to separate a control

8、 besides, more can undertake multiple connections, control powerful easy to achieve overall automation goals, especially with more modification, reusable, extremely is worth popularizing, therefore already popular with automatic control bounded welcome. PLC as a very distinctive and development pros

9、pects of control equipment, mainly used for switch quantity and minority plenty of analogue control system. In the course of industrial production process control, analog quantities of P ID (proportion, integral, differential) adjustment is common kind of control mode, this is due to P ID adjust not

10、 demand for the control system of the mathematical model. Meanwhile P ID regulator and the typical structure, can according to the specific circumstances of the controlled object, using P ID varieties, has the strong flexibility and applicability. The small and medium-sized PLC control system only t

11、o all the way or A few road simulation quantity closed-loop control, hardware only equipped with A/D and D/A conversion module, the software can buy corresponding manufacturefurnished P ID programming function module, need to set the P ID parameters, running P ID control instruction, can accurately

12、control circuit output values.2 problems presented and experiment scheme Nearly zero level temperature control system is a typical industrial control object, which has been widely used in industrial production in the field of various industries, even in daily life temperature control system is commo

13、n. Temperature control system control method of quality, operation effect quality directly affect the quality of the products, energy consumption and production efficiency of equipment. The temperature control system of the controlled object is often more complex, with big inertia, pure, parameter t

14、ime-variance features. Taking A - series B PLC M icro logix1500 and an analog input/output module 1771 - IFE, 1771 - O FE as the main components of temperature control system, driver heating elements in order to achieve what we demand components. Currently USES the conventional P ID control in pract

15、ical production site by parameter setting method of miscellaneous distress, parameter setting, improper performance often poor. Aiming at these problems, we adopted the rockwell RSTuneP ID parameters coordination software, and application to this system to adjust the P ID parameters. In P ID control

16、ler, error signal (controlled system expected temperature and the actual temperature difference between) in added to the temperature control power drive circuit before respectively in three ways (proportion, integral and differential) be amplified. Percentage gain to error signal provides instantane

17、ous response; Points out the error signal gain integration, and will be reduced to connect, the error of integral gain also helps to filter out the actual temperature signal noise, Differential gain driving depends on the actual temperature variation. In many cases, proportion integral control strat

18、egy can also generate meet the requirements of the results, and usually than completely PID controller easier to adjust to the stable operation state, and get to meet the requirements of stable time.3 the temperature control system design A - B series of PLC and an analog input/output unit Micro log

19、ix1500 is A - B company produces A powerful Micro programmable controller, which adopting two type hybrid structure, it has the extensible Compact I/O, built-in P ID, real-time clock RTC function and two road, it also 20kHz high-speed counter built-in 2 analogue fine-tuning potentiometer. Input cell

20、 IFE is A piece of intelligent 1771 - block transmission module, it will be an analog input signals to transmit ability of any kind with A - B PLC interface, and will analog quantities (such as temperature, pressure) converting A proportional 12 binary number or A four BCD value, after conversion va

21、lue stored in the memory module, through block transfer instructions sent to PLC. Each module can be configured at most 16 road one-port input or no.8 differential input. Output module 1771 - O FE has four output channel, in every channel can be binary or four BCD converted into analog signals to dr

22、ive the corresponding amount of output device. Control system design principle electric heating temperature control system mainly consists of heating element, heating equipment, insulating material, power regulator and temperature sensor (thermocouple) components etc. The temperature control system

23、see figure 1. Figure 1 temperature control system diagramBy adjusting the bidirectional thyristor the hige to adjust the output power of DianLuSi by temperature test components thermocouple will to collect of furnace temperature signal through frequency-field, become the digital quantity to PLC. Wit

24、h a better program compiled on the calculation, get the actual temperature, again with a given temperature compared to get through the deviation of the operand, and the output P ID the digital quantity after analog-to-digital conversion, again by output module for silicon controlled voltage regulato

25、r, produce SCR pulse triggered signals, this signal trigger thyristor circuit, in the final analysis, by the circuit drive electric furnace heating silk. By adjusting the thyristor trigger signal (i.e., adjusting voltage supply each cycle of the conduction angles), can control of electric voltage hige and size, thus achieve the purpose of temperature control.