Novel switching control technique for bridgeless PFC to reduce both switching and conduction losses

Abstract

The main theme of this paper is to propose a novel switching control method for bridgeless PFC converter to improve the efficiency by reducing both switching and conduction losses. Comparing to the conventional method, the power device is always on (no switching loss) to provide a current path via the turn-on resistor of MOSFET to reduce conduction losses under light load condition. As the load increases, the power device is always off (no switching loss) to provide a current path via the body diode of MOSFET to reduce conduction losses under heavy load condition. In this paper, both simulation and experimental results will be shown to confirm the effectiveness of the proposed switching control method. Test results derived from a digital-controlled 1.2 kW PFC show the efficiency improvement can go up to 0.73% and 0.57% under full load and light load conditions, respectively. It will also be confirmed this efficiency improvement has no impact on the power factor and just simply changing the switching control method. Both measured steady state and transient waveforms will be shown for confirmation.