Modeling of ZVS Transitions for Efficiency Optimization of the Phase-Shifted Full-Bridge Topology

Abstract

The emergence of wide bandgap semiconductors paved the way for integration of high-efficiency, high-power-density converters into industrial applications. Key to achieving these performance goals is operation at high switching frequencies, which requires mitigation of switching losses by schemes, such as zero-voltage switching (ZVS). The phase-shifted full-bridge (PSFB) converter is a very appealing converter for such industrial applications. However, the mechanisms that underlie the operation of ZVS within this topology are complex, as they depend on the coupled influence of multiple system parameters. This article aims to provide a detailed analytical treatment of the ZVS mechanisms within this topology, along with a detailed study of the interdependence of the associated critical system parameters. A prototype 10-kW, SiC-based PSFB converter is employed to aid this discourse and provide empirical validations. The outcome of these studies is leveraged to identify a set of practical guidelines for tuning the ZVS mechanisms. These guidelines also consider the impact of practical nonidealities, which are often neglected in the literature. Overall, the theoretical formulations, parametric trade studies, and practical implementation suggestions presented in this article constitute a set of tools that designers can utilize to obtain the full performance entitlement of this topology in practice.