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青岛理工大学毕业设计（论文）

摘 要

中央空调已经广泛应用于商用与民用建筑中，用于保持整栋建筑温度恒定。传统的设计中，无论季节、昼夜和用户负荷的怎样变化，各电机都长期固定在工频状态下全速运行，所以会造成极大的的能源浪费。

本设计采用变频器、PLC、温度传感器等器件的有机结合，构成温差闭环自动控制系统，自动调节水泵的输出流量达到节能目的。该系统采用西门子的S7—200PLC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，保证系统根据实际负荷的情况调整流量，实现恒温控制，从而最大程度的解决能源浪费问题。

本设计通过采用基于 USS 协议的RS-485总线通讯的网络，通过西门子 TD200文本显示器实现人机界面的设计，使用 MCGS 工控组态软件，对系统进行理论分析。通过分析该设计，验证了该设计的可靠性，可以解决中央空调的能源浪费问题。

关键词：中央空调，PLC，PID，变频器

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青岛理工大学毕业设计（论文）

ABSTRACT

The central air conditioning has been widely used in commercial and civil buildings, which are used to maintain constant temperature of the building. In traditional design, regardless of the season, day and night, and how the user load changes, the motor is fixed to run at full speed for a long time in the condition of power frequency. It will cause great waste of energy.

This design is developed based on the combination of frequency converter, PLC, temperature sensor. It makes up a temperature difference closed-loop automatic control system and automatically adjust the output flow of pump to achieve energy saving. The system adopts the Siemens S7-200 PLC as the main control unit, using the traditional PID to control algorithm, using Siemens MM440 inverter to control of pump speed, to guarantee system adjust load flow according to actual situation. All of these will bring out constant temperature control, so as to solve the problem of energy waste to a great extent.

This design use RS - 485 bus communication networks which is based on USS protocol and using the Siemens TD200 to realize the human-computer interface design, and using the software made from MCGS, to carries on the theoretical analysis to the system. Verified the reliability of the design, the design can solve the problem of central air conditioning energy waste through the analysis of the design.

KEY WORDS: The central air conditioning, PLC, PID, frequency converter

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青岛理工大学毕业设计（论文）

目 录

摘 要.............................................................................................................................. I ABSTRACT .................................................................................................................. II 第1章 绪论.................................................................................................................. 1

1.1 中央空调的发展.............................................................................................. 1

1.1.1 中央空调现在状况................................................................................ 1 1.1.2 中央空调发展趋势................................................................................ 1 1.2 本设计的意义.................................................................................................. 1

1.2.1 设计的主要内容.................................................................................... 1 1.2.2 设计的意义............................................................................................ 2

第2章 中央空调系统介绍.......................................................................................... 3

2.1 中央空调结构.................................................................................................. 3

2.1.1 中央空调概述........................................................................................ 3 2.1.2 中央空调结构........................................................................................ 3 2.2 中央空调系统工作原理.................................................................................. 4

2.2.1 制冷原理................................................................................................ 4 2.2.2 工作原理................................................................................................ 4 2.2.3 中央空调的控制原理............................................................................ 4 2.3 中央空调的评价.............................................................................................. 5 2.4 本章小结.......................................................................................................... 5 第3章 中央空调控制系统的硬件设计...................................................................... 6

3.1 变频器.............................................................................................................. 6

3.1.1 变频器的介绍........................................................................................ 6 3.1.2 变频调速的原理.................................................................................... 6 3.1.3 变频器的选择........................................................................................ 9 3.1.4 使用注意的问题.................................................................................. 10 3.2 电机的软启动原理及应用............................................................................ 11

3.2.1 软启动的介绍...................................................................................... 11 3.2.2 软启动工作原理.................................................................................. 11 3.2.3 软启动的优点...................................................................................... 11 3.2.4 软启动与变频器的对比...................................................................... 12 3.3 PLC选型 ........................................................................................................ 12

3.3.1 PLC的工作原理 .................................................................................. 12

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