PLC实现的闭环调速控制系统

【摘要】

随着电力电子技术及控制技术的发展，使得交流变频调速在工业电机拖动领域得到了广泛应用。由于PLC的功能强大、容易使用、高可靠性，常常被用来作为现场数据的采集和设备的控制。组态软件技术作为用户可定制功能的软件平台工具，在PC机上可开发出友好人机界面，通过PLC可以对自动化设备进行“智能”控制。

经过研究分析确定在本系统中采用通用变频器MM420，对电机进行转速调节，实现了能源的充分利用和生产的需要。此变频器的FS型加减速功能和转矩提升功能，能很好的解决转速之间的切换。系统中PLC完成数据的采集和对变频器、电机等设备的控制任务。基于S7—200 PLC的编程软件STEP 7，采用模块化的程序设计方法，减少了软件的开发和维护。利用组态软件良好的人机界面和通信能力，使工作人员可以在中央控制室的PC机上就可以方便的浏览现场的工业流程、实现变频器的参数设置、故障诊断及电机的启动和停止。

本文综述了组态软件、PLC技术、变频调速技术的概况。分析了PLC的基本原理，变频调速的基本原理、变频器的结构及其控制算法等变频调速技术。

关键词： PLC、、变频调速、PID调节

Abstract:With the development of electric power and electronic technology and control technology,AC frequency conversion velocity modulation technology is widely used in theindustry motor dragging fields.Because of the characteristics with powerful function,easy operation and high dependability,PLC is usually used for the field of data gathering andequipment control.Configuration software technology is one software platform tool that with custom-made function,friendly human-machine windows,which can be developed on the PC machine,used the PLC to intelligently control the automatic equipment．

Through the rigorouse research and analysis,this system adjusts general transducer KASUGA+Mini MM420 to control the speed of motor,consequently actualizes the full use ofenergy and the need of production．The transducer’s functions of adding or decreasing speedin S form and promoting torque can solve the adjustment of speeds well．In this system，PLC is used to collect data and control equipments such as electromotor and transducer.Based on S7-200 PLC’s programming software STEP 7.which adopts the modularization method inprogramming design,can reduce the software exploitation and maintenance.By the virtue of HMI with nice configuration software and strong communication ability,the staff can conveniently browse the industry flowFig on the locale,set the parameter of the transducer,diagnose the fault,and start or stop the electromotor on the PC machine in the control-centerr00m．This paper summarizes the configurationsoftware technology,PLC technology and AC frequency conversion for speed adjustment technology．

Key words:PLC,cold-rocold rolling mill,Frequency conversion velocity modulation,PID regulator

目录

1 绪论................................................................................................................................................. - 1 -

2 S7-200 PLC的构成........................................................................................................................ - 2 -

2.1S7-200CPU224型PLC的结构 (2)

2.2CPU224型PLC的技术参数 (4)

2.3S7-200PLC的构成 (5)

2.4PLC的工作原理 (13)

3 系统硬件选择............................................................................................................................... - 16 -

3.1西门子S7-200型PLC (16)

3.2EM235模拟量模块 (16)

3.3M ICRO M ASTER420变频器 (18)

3.4PID调节原理 (19)

4 PLC编程设计................................................................................................................................ - 20 -

4.1梯形图 (20)

4.2语句表 (24)

4.3功能块图 (26)

结束语 (30)

致谢 (31)

参考文献 (32)