电子机电论文编号:JD561 附原理图,论文字数:19762,页数:50

 目   录

1绪论………………………………………………………………………………………1
1.1  本课题的目的和意义 …………………………………………………………………1
1.1.1  无刷直流电动机的发展……………………………………………………………1
1.1.2  无刷直流电动机的优点及应用……………………………………………………1
1.2   无刷直流电动机国内外研究动态……………………………………………………3
1.3   无刷直流电动机控制系统的发展…………………………………………………3
1.4   本课题的要求…………………………………………………………………………4
2  无刷直流电动机的基本工作原理………………………………………………………5
2.1  基本组成环节…………………………………………………………………………5
2.2  无刷直流电机本题结构及原理框图…………………………………………5
2.3  基本工作原理 …………………………………………………………………………7
2.4   两两导通方式………………………………………………………………………10
2.5   主要器件的选择  …………………………………………………………………11
2.5.1  单片机的选取………………………………………………………………………11
2.5.2  位置传感器的选择…………………………………………………………………13
2.5.3  驱动电路开关元件的选择…………………………………………………………14
2.5.4  I/O口扩展8155芯片 ……………………………………………………………14
3  无刷直流电机控制策略 ………………………………………………………………17
3.1  直流调速系统…………………………………………………………………………17
3.2  PWM调速基本原理  …………………………………………………………………17
3.3  控制设计………………………………………………………………………………18
4  控制系统硬件设计 ……………………………………………………………………20
4.1  时钟电路 ……………………………………………………………………………20
4.2  PWM发生电路  ………………………………………………………………………20
4.3   LM621 ………………………………………………………………………………21
4.4   全桥驱动电路设计 …………………………………………………………………24
4.5   看门狗电路 …………………………………………………………………………25
4.6   数据存储器扩展电路 ………………………………………………………………26
4.7   LED显示电路 … …………………………………………………………………27
4.8   超限报警电路 ………………………………………………………………………29
4.9   键盘电路 ……………………………………………………………………………30
4.10  电源电路设计………………………………………………………………………31
5  软件设计 ………………………………………………………………………………33
5.1  主程序流程图 ………………………………………………………………………33
5.2  测速子程序流程图 …………………………………………………………………34
5.3  显示子程序流程图 …………………………………………………………………35
5.4  键盘子程序流程图 …………………………………………………………………36
6  程序编译 ………………………………………………………………………………37
结论………………………………………………………………………………39
致谢 ……………………………………………………………………………40
参考文献………………………………………………………………………………41
附录A  程序设计………………………………………………………………………43
附录 B  控制系统原理图

  摘 要
 永磁无刷直流电动机是近些年来发展起来的一种新型电机，其利用电子换相技术代替直流电动机电刷换向的机电一体化产品。它既具有一般直流电动机的运行效率高、起动转矩大、调速范围广和机械特性为线性等优点，又具有交流电动机的结构简单、运行可靠、维护方便等优点。
本文首先论述了永磁无刷直流电动机的基本构成及工作原理。从控制角度对无刷直流电动机的控制策略进行了简单的介绍。本设计主要完成以AT89C51单片机为核心的PWM直流电机的调速系统。该系统包括速度设定、速度显示、速度测量、速度控制、正反转控制、声光报警等。论文介绍了基于单片机用PWM实现直流电机调速的基本方法，直流电机调速的相关知识，及PWM调整的基本原理和实现方法。转速测量和转速设定的显示由4个LED实现。主电路采用MOSFET三相逆变桥，换向电路采用电机专用芯片LM621以减轻单片机用子不断换相所造成的负担.

关键词：无刷直流电机，脉宽调制，转速测量，LM621

Title    Design on the control system of brushless DC motor        

Abstract
Brushless DC Motor with permanent excitation is a new special motor developing in recent years, which changes its phases through the electronic units. It is a production which includes the feature of mechanics and electrical engineering. This new motor has not only the same good characteristics of speed control, high efficiency and high rise torque as traditional DC motor, but also the same good characteristics of simple structure, stable reliability, easy maintainance of AC Motor Brushless DC motors.
At the beginning, we illustrate the fundamental components and the basic working principle of PM-BLDCM. Then the control strategy is introduced at the aspect of theory. A speed governing system of DC-motor by using AT89C51 microcontroller is introduced .The system includes the setting of speed the displaying of speed，the measurement of speed ,aubidle and visual alarm and the control of speed. This paper introduces a kind of method Of DC-motor speed modification based on PWM theory by the SCM. Showing some relative knowledge upon the DC-motor timing，the basic theory and the way to implement. The circuit of rotational speed measuring and setting is presented by four LED. The main-circuit adopts MOSFET three-phases converter. Commutate circuit adopts LM621 to lighten the burden of Single-chip microcomputer. The PWM controller controls the speed.
Key Words  Brushless DC Motor, PWM, Measurement of rotating speed, LM621