In this system, the system has two control loops of frequency conversion and power frequency. On the basis of the original power frequency starting system, the inverter control system is added to ensure that the air compressor can be started at the power frequency after the inverter fails, without affecting production. Through the built-in PID function of the frequency converter, the constant pressure control of the air compressor is realized. The frequency conversion operation of the motor can keep the outlet pressure of the air storage tank stable, and the pressure fluctuation range cannot exceed ±0.2bar.