Active-Clamped Zero-Current Switching Current-Fed Half-Bridge Converter

This article presents an auxiliary circuit for the current-fed half-bridge (CFHB) converter, aiming to clamp the high voltage spikes across the main switches caused by the energy stored in the leakage inductance of the transformer. This circuit also provides zero-current switching (ZCS) to the main switches at turn-off. Moreover, the rectifier diodes and the auxiliary switch operates under ZCS at turn-on and turn-off. Another feature of the proposed circuit is that it is composed of just one active switch, reducing the number of auxiliary sources and drivers compared to the conventional active-clamped CFHB converter. In addition, the inclusion of the clamping circuit increases the voltage ratio of the converter. A 300-W prototype was built to validate the analysis and design proposed in this article. The converter was tested for various load conditions at 100 kHz, and a peak efficiency of 96.2% was obtained. Also, a comparison of efficiency for the CFHB employing other conventional clamping circuits is presented.