Analysis, design and implementation of a zero voltage switching two-switch CCM flyback converter

This study presents a two-switch continuous conduction mode pulse width modulation flyback converter that employs an LC snubber circuit. The snubber circuit is used to achieve zero voltage switching (ZVS) operation for the main switches during the turn-off transition and soft switching for power diodes. With the proposed LC snubber, the magnetic energy in the transformer leakage inductance can be fully recycled and transferred to the input side. The resonant circuit consists of a resonant inductor, a resonant capacitor and two diodes. The operating principles, theoretical analysis and the design methodology of ZVS two-switch continuous conduction mode (CCM) flyback converter are presented. A 200 W (50 V/4 A) laboratory prototype of the proposed converter, operating at a switching frequency of 300 kHz is built to verify the theoretical analysis. At full load the efficiency is 94%.