Wide Range ZVS Phase Shift Full Bridge Converter with Low Conduction Loss

Abstract

The conventional phase shift full bridge (PSFB) converter is widely used for front-end DC/DC stage of distributed power system (DPS). However, hold-up time requirement limits its operating duty ratio in normal operation and it results in the increase of conduction loss in conventional PSFB converter. Therefore, wide range ZVS PSFB converter with low conduction loss is proposed in this paper. The proposed converter adopts the large resonant inductor and replaces clamp diodes in conventional PSFB converter with MOSFET switches. With this modification, the proposed converter can achieve the ZVS operation over wide load range as well as can reduce the conduction loss of switches caused by the circulating current. There advantages result in the improvement of whole load efficiency. The operational principle and analysis of proposed converter are presented and verified by the 1.2kW prototype.