Abstract: A new general PWM modulator for singlephase PFC corrector with one cycle control is proposed in deducing general singlephase PFC governing equation. The PWM modulator is used in singlephase Boost topology. The singlephase Boost PFC corrector's control law is deduced. In view of popular singlephase Boost PFC corrector based on one cycle control, an improved singlephase power factor corrector is proposed. A resistance compensating network and an accumulator are added in the improved corrector, its main circuit inductance revises for the centertapped inductance. Other basic parameters are as same as the popular singlephase PFC corrector. Thus the inductance current ripple distortion is eliminated. The distortion introduced by the DCM is reduced in the certain degree. And the reliability of PFC corrector is also enhanced. Finally experimental results of improved PFC corrector are given. It shows that the improved corrector can greatly enhance the system's power factor. Its power factor can reach 0.994.

Key words: power factor correction（PFC）, PWM, total harmonic distortion (THD) , one cycle control