A NEW ZVS LCL-RESONANT PUSH-PULL DC-DC CONVERTER TOPOLOGY

A new LCL resonant dc-dc converter topology is presented in which the resonant CL components are located after the output rectifier diodes. The push-pull converter topology is suitable for unregulated low-volta ge to high-voltage power conversion, as in battery-powered systems, wh ere input currents can exceed input voltages by an order of magnitude. The resonant circuit operates at twice the switching frequency, allow ing for small resonant components, The MOSFET primary switches operate under zero-voltage switching (ZVS) conditions due to commutation of t he transformer magnetizing current and the snubbing effect of the inhe rent drain-source capacitance. Output rectifier turn-off is effectivel y snubbed by the resonant capacitor. Laboratory tests show 93% efficie ncy at 12-V 160-A input, 235-V 1.8-kW output. Surge capability of up t o 5 kW for 1 s has been tested. Circuit simulations and experimental r esults are presented and are shown to have excellent agreement with fu ndamental mode analysis.