分析了他励直流电机的调速方式,最终选用调压调速作为本系统电机的调速方式。详细分析了PWM信号调节电压的基本原理,采用了定频调宽的方式调节电机两端电压。采用MC9S12XS128作为主控制器,其PWM模块产生的PWM信号控制MOSFET的开通与关断。采用H桥驱动电路驱动直流电机,可以实现直流电机速度的平滑调节,也可以实现车辆的前进、刹车和倒车。为了实现速度的稳定调节,采用了速度闭环的控制策略,通过光电编码器测量车速,与给定信号相比较,给出PWM调制信号,实现速度的稳定调节。 He analyzed the speed regulation mode of DC motor, and finally chose speed regulation as the speed regulation mode of this system. The basic principle of adjusting the voltage of PWM signal is analyzed in detail. The method of adjusting the frequency is adopted to regulate the voltage across the motor. Using MC9S12XS128 as the main controller, the PWM signal generated by its PWM module controls the turn-on and turn-off of the MOSFET. Driving circuit using H-bridge DC motor, DC motor speed can be achieved smooth adjustment, but also can achieve the vehicle forward, brake and reverse. In order to achieve a stable speed regulation, a speed closed-loop control strategy is adopted. The speed of the vehicle is measured by a photoelectric encoder. Compared with a given signal, a PWM modulation signal is provided to achieve a stable speed regulation.