Series LC Resonance-Pulse Based Zero-Current-Switching Current-Fed Half-Bridge DC-DC Converter

This paper proposes a novel zero-current switching (ZCS) current-fed half-bridge DC-DC converter for high voltage gain applications. The proposed converter enables soft-commutation at device turn-off by utilizing resonance between transformer leakage inductance and a series capacitor placed on the primary side of the high frequency transformer. Existing current-fed converters experience turn-off voltage spikes and uses several methods to achieve soft switching which further increases circulating current and limit soft commutation at light-loads. To address these limitations, series LC resonance pulse structure has been proposed where variable frequency control with variable duty is employed to achieve ZCS operation over wide range of load and input variations. Operation of the proposed converter is presented and validated with simulation and experimental results for 500W laboratory prototype.