Multi-output auxiliary power supply with lossless snubber

A multi-output auxiliary power supply realized by a flyback converter is presented for providing the essential low power supplies for control circuits and driving circuits in power processing systems. In the proposed circuit topology, lossless snubbers are introduced intothe flyback converter to recover energy trapped in leakage inductor of transformer, and as a result, smoothes out voltage surge across drain-source of the switch, and alleviates oscillation caused by parasitic capacitance of the switch and leakage inductance of the transformer, hence reduces switching losses and improves conversion efficiency. Based on these concepts, an auxiliary power supply with five sets of output voltage has been designed and implemented to verify the feasibility of the proposed multi-output auxiliary power supply. Experimentalresults show that the conversion efficiency has been increased about 5% and reached 82.5% under full load as compared with flyback converter with hardswitching.