Zero-current-switching (ZCS) power factor pre-regulator (PFP) with reduced conduction losses

This paper proposes a new boost power factor pre-regulator (PFP) featuring zero-current-switching (ZCS). By employing an improved ZCS pulse-width-modulation (PWM) switch cell, ZCS of all the active switches is achieved without additional current stress of the main switch. The additional conduction losses are minimized, 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. Design guidelines with a design example are described and verified by experimental results from the 1.2 kW prototype boost PFP.