A half bridge flyback converter with ZVS and ZCS operations

An asymmetrical half bridge flyback converter without output inductor is presented in this paper, in which the power switches can be turned on with ZVS and the output diode can be turned on and off with ZCS. While the ZVS is obtained from the magnetizing current, the ZCS is achieved from the resonant current. The ZVS and ZCS conditions can be maintained for full load range. The characteristics of the proposed converter rely on the utilization of resonant inductor and blocking capacitor as resonant energy delivery devices rather than linearly charging and discharging components. The operational principle and circuit analysis of the proposed converter is described in this paper. The experimental test of a 90W prototype converter is performed and the results are presented.