An isolated fully soft-switched flyback converter with low voltage stress

An isolated fully soft-switched PWM flyback power converter topology with low switch voltage stress is proposed. The power converter features the use of the leakage inductance of the `flyback´ coupled inductors to achieve zero-voltage switching (ZVS) and/or zero-current switching (ZCS) of all switching devices. The method of implementation is simply to add an additional auxiliary circuit, consisting of a switched LC circuit to the conventional PWM flyback power converter. No extra active or passive voltage clamp circuit is needed to suppress voltage stress on the switching devices. A complete steady-state DC analysis and the operating principle are described. The performance of a 80 W experimental power converter prototype with dual output voltages is presented