A zero-voltage and zero-current switching full bridge converter using an auxiliary circuit

Abstract

This paper analyzes the conventional zero-voltage and zero-current switching (ZVZCS) converters and proposes a new ZVZCS converter. The proposed converter is based on a conventional phase-shifted full-bridge (PSFB) converter and an auxiliary half bridge inverter and an auxiliary center-tapped rectifier are adopted. The auxiliary circuit resets the primary current of transformer in the PSFB converter during the freewheeling period. Therefore, the zero-voltage switching (ZVS) characteristic for the leading leg switches is still remained and a zero-current switching (ZCS) characteristic for the lagging leg switches is newly achieved in proposed converter. Also ZVZCS condition of the auxiliary circuit is naturally realized using the operation of the PSFB converter. The multilevel voltage shown at the output filter reduces the filter size of the proposed converter. To verify the effectiveness of the proposed circuit, operational principle and experimental results will be presented with a 1.6kW specification.