摘要:本文介绍了基于PLC的中央空调控制系统总体结构和工作原理。随着变频技术日趋成熟,利用变频器、PLC、数模转换模块、温度传感器等,可构成温差闭环自动控制系统,自动调节水泵的输出流量,实现中央空调节能效果。首先,介绍了空调系统总体结构。采用西门子S7-200 PLC作为主控制单元,利用传统 PID 控制算法,通过西门子 MM440 变频器控制水泵运转速度。根据实际负荷的情况调整流量,实现恒温控制,节约大量能源。通过对中央空调的理论分析,验证了以出回水温差为根据对其进行变流量控制的可靠性。然后,对变频控制系统进行了设计,为实现温度信号远距离传送,设计了基于 USS 协议的RS-485总线通讯的网络。最后,使用 MCGS 工控组态软件进行系统组态设计与研究。57852
毕业论文关键词:中央空调,PLC,变频器,PID
Abstract: This paper recommend the central air conditioning control system based on PLC overall structure and working principle. Along with the frequency conversion technology has become increasingly mature, with frequency converter、PLC、D/A conversion module、temperature sensor and so on, Can constitute a temperature difference closed-loop automatic control system, Automatically adjust the output flow of pump, Implement the central air-conditioning energy saving effect. First of all, Introduces the general structure of air conditioning system. The Siemens S7-200 PLC as the main control unit, Using the traditional PID control algorithm, By Siemens MM440 inverter control of pump speed. According to the actual load of adjusting flow, To realize temperature control, A large number of energy saving. Through the theoretical analysis of central air conditioning, Verified by the return water temperature difference according to the reliability of the variable flow control on it. And then, The design of frequency conversion control system, To realize temperature signal remote transmission, Based on USS protocol of RS - 485 bus communication network. In the end, Using software made from MCGS system configuration design and research.
Keywords:Central air conditioning, PLC, frequency converter, PID
1 绪论 4
1.1中央空调控制系统的发展和现状 4
1.2 本文研究的主要内容 4
2 中央空调变流量控制原理 5
2.1 中央空调系统的构成 5
2.2 中央空调系统制冷原理 5
2.3 中央空调变流量控制的原理 6
2.4 电机变频器软启动应用 6
2.5 PID温度控制的设计 6
3 央空调控制系统的硬件设计 8
3.1 MM440变频器的工作原理 9
3.2 PLC的选型 10
3.3 PT100温度传感器 11
3.4 PT100温度变送器 11
3.5 人机界面设计 11
3.6 中央空调系统的硬件设计 11
4 软件设计 15
4.1 PLC编程软件简介 15
4.2 PLC初始设定 15
4.3 PLC主程序流程图 18
4.4 PLC程序设计 18
4.5 MCGS组态及系统仿真 20
结论