Multi-output auxiliary power supply with lossless snubber

Abstract

A multi-output auxiliary power supply realized by a flyback converter is presented for providing the needed low power supplied for the control circuits and driving circuits in power processing systems. In the proposed circuit topology, lossless snubbers are introduced into the flyback converter to recover energy trapped in leakage inductor of transformer, to smooth out voltage across drain-source of switch, and to alleviate oscillation caused by parasitic capacitor of diode and the leakage inductor of transformer, hence reducing switching loss and improving conversion efficiency. Based on these concepts, an auxiliary power supply with five sets of output voltages has been designed and implemented to verify the feasibility of the proposed multi-output auxiliary power supply. Experimental results show that the conversion efficiency has been increased about 5% and reached 82.5% under full load as compared with flyback converter with hard-switching.