A Boundary-Mode Forward-Flyback Converter With an Efficient Active LC Snubber Circuit

This paper describes a boundary-mode forward-flyback converter (BMFFC) with zero-voltage switching that is able to process power efficiently. The theoretical analysis and operating principle of the BMFFC are presented in detail. A nondissipative LC snubber that recycles energy to the input source is employed in order to suppress the voltage spike caused by the leakage inductance of the transformer. The relatively large snubber capacitor also significantly reduces turn-off loss. Following a detailed design procedure, a 200 W prototype with a 25-50 V dc input and 230 V dc output was constructed and tested in order to evaluate the performance of the BMFFC.