毕业论文：基于单片机的温度控制系统的硬件设计.doc

PAGE  PAGE 39 基于单片机的温度控制系统的硬件设计 摘 要 本文针对温度控制的特点，提出了单片机温度控制系统的硬件设计方法，同时也对温度控制系统的控制过程做了理论分析，建立了控制系统的数学模型，提出了克服温度控制系统中纯滞后影响的控制方法。 该单片机温度控制系统由键盘、AD采样、PWM控制与显示四部分构成。其中，键盘输入给定温度值；由AD574将采集的温度转换为数字量送入单片机；通过PWM控制调节脉冲的宽度，从而获得所需要的输入与输出电压；最后由LED显示给定温度与检测温度值。 温度控制系统普遍存在大延时、纯滞后的特性，常引起系统产生超调和震荡，使控制系统的稳定性降低。因此，本设计采用史密斯预估器对系统进行纯滞后补偿，以此消除系统的超调和震荡，使系统稳定。文中给出了控制系统的数学模型，确定了系统控制方案和控制系统的硬件电路框图，本设计可直接应用于工业控制中。 本设计通过PROTEUS软件对系统的硬件进行仿真，通过MATLAB/SIMULINK的仿真结果验证数字控制器设计的正确性。 关键词：温度控制，单片机，纯滞后，史密斯预估器 The hardware design in temperature control system based on Microcontroller Abstract This article narrates the hardware design in temperature control system. Aiming at temperature control problem which industry produce usually occurs. We can use the software and the hardware source of the single chip microcomputer (AT89C51) to check, control and display the temperature value on real-time. The settle temperature value is input by the keyboard. Here we make the system to follow this settle value,and finally to attain the purpose of automatic control. This temperature control system is mostly made of four parts which consists of the keyboard,AD sampling circuit, PWM control and LED real time display part.Among of them,keyboard inputs the settle value.AD574 transforms the temperature into digital signal and sends it into single chip microcomputer.PWM control circuit regulates the width of pulse in order to attain input and output voltage that needed.At last, LED real time display part displays the settle value and detected value. The temperature control system usually contains great postpones and pure hysteresis characteristic which often causes the system to produce super surge and make its stability lower. The mathematics model has been given in this article in order to definite the control program and hardware electrocircuit diagram of the system. This design may apply directly in the industrial cnntrol. This design use the PROTEUS to make a simulation of departments hardware ,passes MATLA