Soft Switching Isolated Sepic Converter with the Buck-Boost Type of Active Clamp

A zero voltage switching (ZVS) isolated Sepic converter with active clamp topology is presented. The buck-boost type of active clamp is connected in parallel with the primary side of the transformer to absorb all the energy stored in the transformer leakage inductance and to limit the peak voltage on the switching device. During the transition interval between the main and auxiliary switches, the resonance based on the output capacitor of switch and the transformer leakage inductor can achieve ZVS for both switches. The operational principle, steady state analysis and design consideration of the proposed converter are presented. Finally, the proposed converter is verified by the experimental results based on an 180 W prototype circuit.