摘要本文主要介绍了一种基于应用广泛的单片机AT89S51实现的数字式双闭环PWM直流调速系统，包括硬件实现电路和软件实现方法，并由工程设计方法解决调节器的设计问题，再由MATLAB中的SIMULINK仿真软件调试得出调节器的最佳参数。

首先，我们设计双闭环直流调速系统的稳态结构原理图，如图1，并根据选定的电机Z41321计算必要的参数。建立双闭环直流调速系统的的动态数学模型，并运用工程设计方法设计转速、电流负反馈控制的双闭环直流调速系统的调节器ACR、ASR，再利用MATLAB中的仿真软件进行仿真，对设计参数进行必要的修正和调整。

其次，双闭环直流调速系统的控制单元是单片机AT89S51，系统外围硬件电路主要包括键盘单元、显示单元、主电路、A/D转换单元等。由电流互感器检测电枢电流并经A/D转换电路构成系统的电流反馈环，由光电编码器检测转速并构成速度反馈环。用Proteus画出系统的硬件结构图及电路图如图2、3所示。70313

最后，我们根据上述准备的条件，设计系统程序流程图，利用单片机的定时器生成占空比可调的PWM信号，控制由IGBT管组成的H桥可逆PWM变换器，对直流电机进行无级平滑调速。

总之，本设计双闭环控制直流调速系统具有稳定性好，跟随性和抗扰性能优，控制精度高的特点，与设计要求吻合。

该论文有图31幅，表13个，参考文献17篇。

毕业论文关键词：MATLAB  直流调速  AT89C51单片机  PWM  双闭环

Double Closed Loop of DC Speed Control System Based on MCU

Abstract

This essay introduces a digital double closed loop of DC speed control system, which is based on a widely used MCU AT89C51 and powered by PWM speed control system, including hardware circuit and the method of software. We will solve the problem of designing the regulator by Process Design Method. Then we will obtain optimum parameters of the regulators via MATLAB Simulink simulation software. 

First of all, we design a double closed loop DC speed control system of the steadystate structure diagram, as is shown in figure 1,and we will calculate the necessary parameters according to the selected motor Z41321. The dynamic mathematical model of the double closed loop DC speed regulation system is established, and current negative feedback control of double closed loop DC speed regulating system ACR, ASR. And the simulation software of MATLAB is used to simulate the design parameters, and the necessary correction and adjustment will be made.

Secondly, the control unit is a single chip microcomputer AT89S51, the system peripheral hardware circuit mainly includes the keyboard unit, the display unit, the main circuit, A/D conversion unit, etc. The current feedback loop of the system is detected by the current transformer. We use Proteus to draw the system's hardware structure diagram and circuit diagram is shown in Figure 3.2.

Finally, we design the flow chart of system according to the conditions of the preparation, the singlechip timer generates accounting for generator of adjustable duty ratio of the PWM signal, Hbridge reversible PWM converter, controlled by IGBT tube, regulate the DC motor steplessly.

In short, the double closed loop control DC speed regulation system is of good stability, antiinterference ability and high control precision.

Key Words: MATLAB  DC speed regulation  PWM  double closed loop 

目  录

摘要I

AbstractII

目录III

图清单V

表清单VI

变量注释表VII

1 概述1

1.1直流调速系统的概述1

1.2研究课题的目的和意义1

1.3国内外研究现状2

1.4系统设计的要求和内容2