Abstract: This article introduced the control principles and methods of PFC in inverter air-conditiners' designing. By detection the average power current, the instantaneous power current, and the dc bus voltage output, it automatically calculate and control the duty ratio of PWM wave, automatically djust the power supply power factor, realize the dc bus voltage booster and stable. Control model is simple and control is convenient, without too much hardware circuit. Achieve the goal of the ideal power factor automatic adjustment.

Key words: PFC control, Power factor, Dc bus voltage, Duty ratio