An Enhanced Model for Small-Signal Analysis of the Phase-Shifted Full-Bridge Converter

This paper presents an in-depth critical discussion and derivation of a detailed small-signal analysis of the phase-shifted full-bridge (PSFB) converter. Circuit parasitics, resonant inductance, and transformer turns ratio have all been taken into account in the evaluation of this topology´s open-loop control-to-output, line-to-output, and load-to-output transfer functions. Accordingly, the significant impact of losses and resonant inductance on the converter´s transfer functions is highlighted. The enhanced dynamic model proposed in this paper enables the correct design of the converter compensator, including the effect of parasitics on the dynamic behavior of the PSFB converter. Detailed experimental results for a real-life 36 V-to-14 V/10 A PSFB industrial application show excellent agreement with the predictions from the model proposed herein.