摘 要
空气压缩机(简称空压机)是一种用来压缩气体提高气体压力或输送气体的机械。空压机的用途很广，几乎遍及工农业、国防、科技、民用等各个领域。空气压缩机的安全生产保护对于煤矿企业的生产是十分重要的。可编程控制器(PLC)将传统的继电器控制技术、计算机控制技术和通信技术融为一体，专为工业控制而设计。本设计方案采用PLC和变频器实现对空压机组的自动控制。该方案采用变频器实现对空压机“一拖多”的控制，PLC实现变频器的工频与变频的转换控制，以及切换变频器对某台空压机进行控制。系统利用压力传感器采集气包出口压力，通过变送器输出4～20毫安标准信号至PLC模拟输入端口，经过PLC内部PID算法逻辑运算，送出控制信号至变频器，变频器根据送来的信号改变输出电压的频率，来调节电机转速，以确保供气压力的恒定。当变频器控制当前机由变频转为工频，而供气压力仍不满足时，则由PLC控制变频器软启动下一台空压机变频运行，依次开启。当变频器输出电压的频率已降至下限值，而供气压力仍高于所需压力，则由PLC控制变频器关闭当前机，变频器转而变频控制另一台运行的空压机。从而使生产系统获得良好的经济效益和安全性能。本论文介绍了空气压缩机、可编程控制系统（PLC）控制原理、系统通信等。
关键词：空气压缩机；可编程控制器（PLC）控制系统；变频器；PID调节器
ABSTRACT
Air compressor (the compressor) is a compressed gas to increase gas pressure or gas transportation machine. Air compressor is widely used in nearly all industrial and agricultural, defense, science and technology, civil and other fields. Air compressor safety protection for the production of coal mining enterprises is very important.
Programmable Logic Controller (PLC) to the traditional relay control technology, computer control technology and communication technology integration, specifically designed for industrial control of. The design uses PLC and frequency converter to realize the automatic control of air compressor. The program uses inverter of the air compressor \more\control, PLC to achieve the inverter frequency and frequency conversion control, and inverter switching control of a compressor station. Collection system using pressure sensors Outlet pressure air bag, transmitter output by 4 to 20 mA standard signal to the PLC analog input port, through the internal PID algorithm PLC logic operations, sends control signals to the inverter. When the inverter to control the current machine by the inverter frequency, while the gas pressure is still not satisfied by the PLC control inverter frequency soft-start the next station air compressor to run, and then click Open.
When the inverter output voltage frequency has dropped to the lower limit, while the gas pressure is still higher than the pressure required by the PLC control the inverter to close the current machine, inverter switch to another frequency to run the compressor control. So that the production system for good economic and safety performance. This paper describes an air compressor, a programmable control system (PLC) control theory, system communications.
Keywords: air compressor; Programmable Logic Controller (PLC) control system; inverter; PID regulator
目录
1绪论 ............................................................. 1
1.1 PLC控制在国内外的发展近况 ................................. 1 1.2课题的背景和意义 ........................................... 2 2 空气压缩机 ....................................................... 3
2.1空气压缩机及分类 ........................................... 3 2.2螺杆式空压机 ............................................... 4
2.2.1螺杆式空压机基本结构 ................................. 4 2.2.2螺杆压缩机的工作原理 ................................. 4 2.2.3螺杆压缩机的特点 ..................................... 5 2.3活塞式空压机 ............................................... 6 3可编程控制器（plc）控制系统 ...................................... 8
3.1 PLC的产生和发展 ........................................... 8 3.2 PLC基本结构 ............................................... 9 3.3 PLC基本工作原理 ........................................... 9
3.3.1扫描技术 ............................................ 10 3.3.2 PLC的I/O响应时间 .................................. 11 3.4 PLC的主要特点 ............................................ 11 4 基于plc的煤矿空压机控制系统设计方案 ............................ 13
4.1控制系统组成 .............................................. 13 4.2控制系统的工作原理 ........................................ 14
4.2.1空压机切换工作过程 .................................. 19 4.2.2通信方式 ............................................ 21 4.2.3控制系统概述 ........................................ 22 4.2.4 报警装置 ............................................ 27 4.3 系统设计 .................................................. 27
4.3.1 PLC控制系统设计步骤 ................................ 27
4.3.2 PLC程序设计的步骤 .................................. 30 4.4 控制系统硬件设计 .......................................... 30
4.4.1主电路设计 .......................................... 30 4.4.2 PLC选型 ............................................ 33 4.4.3变频器选型 .......................................... 35 4.4.4传感器的选取 ........................................ 36 4.4.5系统PLC硬件部分地址分配及部分程序 .................. 38
5 结论 ............................................................ 41
5.1工作总结 .................................................. 41 5.2毕业设计心得 .............................................. 42 参考文献 .......................................................... 43 致 谢 ............................................................. 44 附录 系统总图 ..................................................... 45