Zero voltage switching active clamp buck-boost stage Cuk converter

The paper presents an active clamp buck-boost stage Cuk converter to achieve soft switching commutation. An auxiliary switch and a clamp capacitor are connected in parallel with the primary side of the transformer to absorb all the energy stored in the transformer leakage inductance. The resonant inductance and the clamp capacitance are resonant to achieve zero-voltage switching (ZVS) of the auxiliary switch. On the other hand, the resonance between the resonant inductance and output capacitance of the main switch will achieve ZVS of the main switch in the proposed converter. The principle of operation and system analysis are presented. Design considerations of the proposed converter are also provided. Experimental results for a 170 W prototype circuit operating at 70 kHz are given to demonstrate the effectiveness of the proposed converter.