简易水温控制系统

一个简易水温控制系统的设计———控制算法设计

摘要

在工农业生产和日常生活中，对温度的检测与控制始终有着非常重要的实际意义和广泛的实际应用。为了加深计算机控制理论的理解，故设计一个温度控制系统，该系统主要由温度信号采集与转换模块、主机控制模块、温度控制模块、液晶显示模块四部分组成，控制算法为PID算法。系统可实现稳态误差小于1℃，最大超调小于1℃，并且调节时间较短，恒定效果好。温度控制系统的对象存在滞后，它对阶跃信号的响应会推迟一些时间，对自动控制产生不利的影响，因此对温度准确的测量和有效的控制是此类工业控制系统中的重要指标。温度是一个重要的物理量，也是工业生产过程中的主要工艺参数之一，物体的许多性质和特性都与温度有关，很多重要的过程只有在一定温度范围内才能有效的进行，因此，对温度的精确测量和可靠控制，在工业生产和科学研究中就具有很重要的意义。本文阐述了过程控制系统的概念，介绍了一个基于数字传感器DS18B20和单片机STC89C52的简单温度控制系统，以电热水壶为被控对象，通过实验的方法建立温度控制系统的数学模型，采用了PID算法进行系统的设计，达到了比较好的控制目的。该系统可通过液晶显示器LCD1602显示数据或字符，通过按键设定参数；通过DS18B20测温，实现电热杯水温控制；通过PL2303下载端口，实现单机和上位机的通讯。实验表明该系统能够实现对温度的控制，具有一定的控制精度。该系统测温电路简单、连接方便，可用于简单温度控制的场合。

关键词：单片机；温度传感器；液晶显示器；PID算法

Abstract

In industrial and agricultural production and daily life, the testing and control of temperature has always had very important practical significance and extensive practical application. In order to deepen the understanding of the computer control theory, the design of a temperature control system, the system is mainly composed of temperature signal acquisition and conversion module, host control module, temperature control module, liquid crystal display module four parts, the control algorithm for PID algorithm. System can realize the steady state error is less than 1 ℃, the maximum overshoot less than 1 ℃, and the adjustment time is shorter, constant effect is good. Lagged temperature control system of the object, its response to the step signal will delay some time, produce adverse effect to the automatic control, so effective for accurate temperature measurement and control is an important indicator in the industrial control system. Temperature is an important physical quantities, it is also one of the main process parameters in industrial production process, many properties of objects and features are related to temperature, a lot of important process can only be effective in a certain temperature range, thus, accurate measurement and reliable control of temperature, in the industrial production and scientific research has the very vital significance. This paper expounds the concept of process control system, introduced a digital sensor DS18B20 and single chip microcomputer based STC89C52 simple temperature control system, electric kettle for controlled object, and through the experiment the method to establish the mathematical model of temperature control system, using PID algorithm to the design of the system, to achieve the better control. Through DS18B20, the temperature control of the electric heat cup is achieved. Through the PL2303 download port, the communication between the single machine and the above machine is achieved. The experiment shows that the system can control the temperature, and has certain control accuracy. The system is simple and easy to connect, which can be used for simple temperature control.

Key words: single chip microcomputer;the temperature sensor;Liquid crystal display;PID algorithm