The cascade buck-boost PFC converter with soft switching

A new cascade buck-boost topology with passive lossless snubber is proposed in this paper, it has been successfully used in PFC circuit of high voltage system. Switching losses and EMI noises are reduced by restricting di/dt of the diode reverse recovery current and dv/dt of IGBT collector-emitter voltage. The IGBT in the buck circuit operates at ZVS turn-off and ZCS turn-on. The freewheeling diode is also commutated with ZVS. An APFC prototype has been built in the laboratory to demonstrate the effects of the circuit. Power factor of this 380 VAC/600 W proof-of-prototype is 0.98 and less than 11% THD can be achieved.