摘 要：本文在研究了利用单片机控制PWM(脉宽调制)信号实现对直流电机转速进行低成本控制的方法基础上，设计了基于89C51单片机的直流电机转速控制系统。系统由单片机主控部分、驱动电路、续流保护电路等部分组成。利用单片机产生固定频率的信号来控制电源的接通或断开，并通过改变直流电机电枢上电压的“占空比”来改变平均电压的大小，从而控制电动机的转速。采用芯片L298作为直流电机调速功率放大电路的驱动模块，并且把它与续流保护电路相结合完成了在主电路中对直流电机的控制与保护。通过单片机结合数码管显示电动机占空比。测试结果表明设计的系统能较好实现对电机的调速功能。68635

毕业论文关 键 词：AT89C51 ，PWM信号，L298芯片 , LED数码管 ， 直流电机

Abstract: This paper studies the use of single-chip control PWM (pulse width modulation) signal to achieve low cost control method based on the speed control of a DC motor, and design based on 89C51 single chip microcomputer DC motor speed control system. The system is composed of the main parts of the microcontroller, the driving circuit, the continued flow protection circuit and so on.. The use of single-chip fixed frequency signal to control the power switched on or off, and by changing the voltage on the DC motor armature accounted for empty than "to change the size of the average voltage, so as to control the motor speed. The chip L298 is used as the driving module of the DC motor speed adjusting power amplifier, and the control and protection of the DC motor in the main circuit are accomplished by combining the chip with the continuous flow protection circuit.. The speed of the motor is displayed by combining the single chip computer with the digital tube. The results of the test show that the system can achieve the motor speed function.

Key words: AT89C51, PWM signal, L298 chip, LED digital tube，Continuous current dynamo

目     录

1  引言 4

1.1  开发背景 4

1.2  选题的目的和意义 4

2  直流电动机总体调速概述 5

2.1  直流电机调速原理 5

2.2  直流调速系统实现方式 6

2.3  AT89C51单片机简介 6

3  系统总体方案论证描述 7

4  系统总体设计框图 7

5  硬件电路模块的设计 8

5.1  驱动放大电路设计 8

5.2  L298集成电路内部结构原理图及管脚功能介绍 8

5.3  LED数码管显示模块 9

5.4  独立式键盘输入控制电机转动原理 10

5.5  续流保护电路设计模块 10

5.6  系统总电路设计与分析 10

6  系统软件设计 11

6.1  PWM实现方式方案论证 11

6.2  主程序设计分析 12

6.3  数码显示程序设计 13

6.4  电机控制功能程序设计 15

7  仿真及调试结果分析