Power factor pre-regulator (PFP) with an improved zero-current-switching (ZCS) PWM switch cell

This paper proposes a new boost power factor preregulator (PFP) featuring zero-current-switching (ZCS). By employing an improved ZCS PWM switch cell, ZCS of all the active switches is achieved without additional current stress of the main switch. The additional conduction loss is reduced, since the circulating current for the soft switching flows only through the auxiliary circuit and a minimum number of switching devices are involved in the circulating current path. The diodes commutate softly and reverse recovery problems are alleviated. The voltage stress of the rectifier diode is reduced compared to the previous ZCS approaches. Design guidelines are described and verified by experimental results from the 1.2 kW prototype boost PFP.