A new ZVS LCL-resonant push-pull DC-DC converter topology

Abstract

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-voltage to high-voltage power conversion, as in battery-powered systems, where input currents can exceed input voltages by an order of magnitude. The resonant circuit operates at twice the switching frequency, allowing for small resonant components. The MOSFET primary switches operate under zero-voltage switching (ZVS) conditions due to commutation of the transformer magnetizing current and the snubbing effect of the inherent drain-source capacitance. Output rectifier turn-off is effectively snubbed by the resonant capacitor. Laboratory tests show 93% efficiency at 12 V, 160 A input, 235 V, 1.8 kW output. Surge capability of up to 5 kW for 1 s has been tested. Circuit simulations and experimental results are presented and are shown to have excellent agreement with fundamental mode analysis.