密级：公开
基于PLC的太阳能热水器自动控制系
统设计
Design of Solar Water Heater Automatic
Control System Based on PLC
学 院： 电气工程学院 专 业 班 级： 自动化1005班 学 号： 100302516 学 生 姓 名： 魏天野
指 导 教 师： 白山（教授级高工）
2014 年 6 月
摘 要
现在，城市居民绝大部分都使用了太阳能热水器，农村也有相当一部分人使用。太阳能热水器在技术上比较成熟、造价比较低廉，同时由于给人民提供绝对安全的热水而受到人们的欢迎，且具有节能、环保、安全、便利、长久等优点，所以它的应用会越来越广。因此，研究和开发先进的太阳能热水器控制系统变得越来越重要。
本设计阐述了可编程控制器（PLC）在太阳能热水器控制系统中的应用,重点研究了系统的硬件构成及软件的设计过程。指出了PLC设计的关键是能满足基本的控制功能,并考虑维护的方便性、系统可扩展性等。本设计利用西门子S7-200PLC，进行了太阳能热水器自动控制系统的I/O分配和PLC选型，编写了PLC程序梯形图和接线图，实现了自动上水排水、自动循环、自动加热、PID闭环控制恒温出水、手动与自动模式切换等功能。并在此基础上，利用S7-200的仿真软件对系统进行了仿真，利用WinCC Flexible软件组态了人机界面，使用MPI通信协议实现了PLC与触摸屏的通信连接。把可编程控制器PLC作为太阳能热水器的控制系统，增加了系统的方便性与可靠性，减少了其它元器件的使用。它使系统接线简单，检修维护方便快捷，增进了系统的先进性。
论文分为四章：第一章介绍了太阳能热水器发展背景及设计意义；第二章介绍了太阳能热水器的工作原理；第三章介绍了硬件选型及系统流程；第四章介绍了系统程序的编写、系统的仿真、人机界面（WinCC Flexible）组态过程。
关键词：太阳能热水器；PLC；自动控制系统
I
Abstract
Now, vast majority of urban residents use solar water heaters, so do a considerable number of rural people. Solar water heaters are technically more mature, relatively low cost. Meanwhile, since it provide absolute security to the people of hot and people are welcome, and it has some advantages of energy saving, environmental protection, safety, convenience, long, etc. So it will be widely applied. Therefore, the research and development of controlling system of advanced solar water heater are becoming increasingly important.
This design expounds the application of PLC in solar water heater automatic controlling system, especially the designing process of hardware and software of the system. Furthermore, the project shows that the key of PLC designing is to satisfy the basic controlling function, considering the convenience of maintenance and scalability. In this design, the address of I/O is resigned and the suitable PLC is chosen. The electrical principle diagram and the interconnection diagram are drawn, according to the requirement. Automatic water drainage, automatic cycle, automatic heating, PID loop control temperature water, manual and automatic mode switching function have been realized. And on this basis, the system was simulated using the simulation software for S7-200, produced a man-machine interface by using WinCC Flexible software. As the controlling system of solar water heater, PLC greatly reduces the number of other components. Moreover, it has the feature such as simple interconnection, rapid and easy fault detecting and maintenance, and advancement of the system.
The paper is divided into four chapters: the first chapter describes the background of the development and design of solar water heaters significance; Second chapter describes the working principle of solar water heaters; Third chapter describes the hardware selection and system processes; The fourth chapter describes the procedures for the preparation of the system, system simulation, HMI (WinCC Flexible) configuration process.
Keywords: Solar water heater; PLC; Automatic control system
II
目 录
摘 要 ..................................................................................................................................... I Abstract ..................................................................................................................................... II 第1章 绪论 .............................................................................................................................. 1
1.1课题研究的背景 .......................................................................................................... 1 1.2国内外研究现状简述 .................................................................................................. 2 1.3太阳能热水器市场分析 .............................................................................................. 3 1.4本设计特点及主要内容 .............................................................................................. 5 第2章 太阳能热水器的组成及工作原理 .............................................................................. 6
2.1太阳能热水器的基本结构 .......................................................................................... 6 2.2太阳能热水器的工作原理 .......................................................................................... 8 2.3本设计要实现的功能 ................................................................................................ 10 第3章 太阳能热水器硬件的选型及设计 ............................................................................ 11
3.1 PLC的工作原理 ........................................................................................................ 11 3.2硬件设备的选型 ........................................................................................................ 13
3.2.1 PLC的选型 ..................................................................................................... 13 3.2.2其他硬件的选型 ............................................................................................. 15 3.3太阳能热水器的整体设计 ........................................................................................ 18
3.3.1 PID闭环控制 ................................................................................................. 18 3.3.2 PLC与外部设备连接方案 ............................................................................. 20 3.3.3水工艺流程设计 ............................................................................................. 22
第4章 系统软件框架的构建与系统仿真 ............................................................................ 23
4.1系统的I/O口地址及相关的软元件功能设置 ......................................................... 23 4.2系统的程序流程图 .................................................................................................... 25 4.3设计控制系统的梯形图程序 .................................................................................... 28 4.4系统仿真 .................................................................................................................... 35 4.5组态人机界面 ............................................................................................................ 39 第5章 结论 ............................................................................................................................ 42 参考文献 .................................................................................................................................. 43 致 谢 .................................................................................................................................. 45 附 录 S7-200仿真监控图 ............................................................................................... 46
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