The output pwm signal of MCU can not be directly added to the switch tube. The opening and cut-off voltage of the pipe can be reached by signal amplification. The single chip microcomputer can control the opening and closing of the switch tube after amplifying PWM signal output by the program. The PWM signal of high voltage and high current formed by the switching tube is obtained. The Shingen signal can be simulated into a sine wave signal of different frequencies. Thus control the motor speed