Analysis and Design of Series LC Resonance-Pulse Based Zero-Current-Switching Current-Fed Half-Bridge DC–DC Converter

This article investigates upon partial resonance in current-fed converter using series LC resonant circuit to attain zero-current-switching (ZCS) of the semiconductor devices. A resonance pulse appears during overlap conduction time of the semiconductor devices causing natural current reduction in an outgoing device to zero before the gating signal is forced-off achieving ZCS commutation of the devices. Soft device turn-off eliminates the turn-off switching losses and more importantly, avoids the traditional requirement of additional snubber to clamp the voltage across the semiconductor devices in current-fed converters. Partial resonance reduces the circulating current and so rms current through the devices limiting the conduction losses. The proposed idea is analyzed and implemented on current-fed half-bridge isolated voltage doubler topology. It has been experimentally demonstrated to achieve wide range ZCS operation along with high efficiency.