Passive lossless snubber with minimum voltage and current stress for boost PFC

Abstract

A passive lossless snubber for boost power factor corrector (PFC) is presented. This snubber has several advantages. First, it does not introduce extra voltage and current stress on the main switch. Second, it provides soft-switching conditions for the main switch over wide input and load range. Third, it limits the turn-on current of the main switch resulting from the reverse recovery current of the output diode. The main switch is turned on with zero current and is turned off with zero voltage. The performance of the proposed snubber has been evaluated experimentally on a 750W PFC with universal input. The boost converter is operated in continuous conduction mode and its input current is shaped by using an average current-mode controller. Experimental results show that soft-switching of the main switch is maintained over 88% with the input of 110V, 60Hz, and 91.8% with the input of 220V, 50Hz, over one line cycle, and from full load to 20% load.