A new active soft-switching circuit for full bridge converters

TLDR: In this paper, an active soft switching circuit for bridge converters aiming at improving the power conversion efficiency is proposed, which achieves lossless switching for both main and auxiliary switches without increasing the main device current/voltage rating.

Abstract: This paper proposes an active soft-switching circuit for bridge converters aiming at improving the power conversion efficiency. The proposed circuit achieves loss-less switching for both main and auxiliary switches without increasing the main device current/voltage rating. It is capable of operating at elevated switching frequencies of several hundreds of kHz, at low and high power levels with a wide range of load variations. A winding coupled to the primary of power transformer ensures soft switching for the auxiliary switches during turn-on and turn-off. Phase Shifted Full Bridge (PSFB) topology is chosen to validate the design. Operation principle with analytical expressions for the proposed circuit are outlined. The proposed active soft switched PSFB DC-DC converter circuit is designed and implemented for 350 W, switching at 100 kHz. The simulation and experimental results are presented. Experimental results are used to validate the analysis.