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1、.摘 要随着时代的进步和科技的发展，电机调速系统在工农业生产、交通运输以及日常生活中起着越来越重要的作用。直流电机是通过两个磁场的相互作用而发生旋转的。定子通过永磁体或受激励电磁铁产生一个固定磁场，转子由一系列绕组和导磁材料构成，电流通过每个绕组时都会产生磁场。对有刷直流电机而言，转子上的换向器和定子上的电刷在电机旋转时为每个绕组供给电能。通电转子绕组与定子磁体有相反的极性，通过相互吸引而产生转矩使转子转动。电机的速度与施加的电压成正比，转矩则与电流成正比。对直流电机的控制是一个挑战，因为必须在工作期间改变直流电机的速度。使直流电机高效运行最常用的的方法是施加一个 PWM（脉宽调制）方波，其通
2、断比率对应于所需的速度。电机起到一个低通滤波器的作用，它将 PWM 的信号转换为有效直流电平。本次实训采用 STC89C52 单片机与 L298N 驱动芯片驱动直流电机工作，单片机控制的直流脉冲（PWM）调速及旋转方向控制系统，并且详细论述了该系统的控制方法、结构、参数设计、程序设计等方面的问题。该系统结构简单，调速性能好，性能价格比高，真正实现了直流电机调速系统及旋转方向的控制。关键词：关键词：直流电机；STC89C52 单片机； L298N 驱动电路.AbstractWith the progress of the times and the development of science
3、and technology, motor speed control system in the industrial and agricultural production, transportation and daily life plays an increasingly important role in. DC motor is accomplished by a two magnetic field interactions which occur rotation. The stator by permanent magnets or stimulated the elect
4、romagnet produces a fixed magnetic field, the rotor is composed of a series of winding and the magnetic materials formed, the current through each winding will generate a magnetic field. The brush DC motor, rotor and stator of the commutator brush in the motor rotates for each winding supplies elect
5、rical energy. Energized rotor winding and the stator magnets have opposite polarity, through attraction to produce torque rotating the rotor. The speed of the motor and the applied voltage is proportional to the torque is proportional to the current, and the. For the DC motor control is a challenge,
6、 because must be at work during changing the speed of DC motor. The DC motor is the efficient operation of most commonly used method is applied to a PWM ( pulse width modulation ) square wave, the on-off ratio corresponding to the desired speed. The motor has a low pass filter function, it will PWM
7、signal is converted to an effective level. The design of STC89C52 monolithic integrated circuits to control the PID the direct pulse （PWM ） machinery velocity modulation system, and elaborated on the system of control methods, structure and design, the application design problems. the system simple
8、and good performance machinery velocity modulation prices are high, really to direct the electrical machinery velocity modulation control system of high-precision.Key words：monolithic integrated circuits, a direct motor, machinery velocity modulation system.引言.4 1 系统硬件介绍.4 1.1 硬件主控芯片概述及功能介绍.4 1.1.1 STC89C52 单片机主控制电路图.4 1.1.2 L298N 直流电机的专用驱动器 .5 1.2 硬件电路设计.7 1.2.1 显示电路的设计.7 1.2.2 键盘电路的设计.7 1.2.3 电机驱动电路的设计.8 2 系统软件设计.9 1.1 设计要求.9 1.2 总体设计方案.9 1.2.1 设计思路.9 1.2.2 方案论证与设计.9 1.2.3 系统组成.9 3 硬件制作、调试与软件.10 3.1 系统 PCB 板的设计.10 3.2 系统硬件调试.11 3.3 主控程序.11 4 实训心得体会.11 谢 辞.14
