A Phase-Shift Triple Full-Bridge Converter With Three Shared Leading Legs

This paper proposes a novel phase-shift triple full-bridge (PSTB) converter, in which all the three bridge legs are the leading legs. Thus, the switches can realize zero voltage switching over the full load range in a short time without the assistance of the series inductance. The primary-side circulating current is utilized to transfer energy from the input to the output, so that the circulating loss can be reduced significantly. Furthermore, the PSTB converter has high power density and strong robustness to open-circuit failures. Therefore, the PSTB converter would be useful for full load range and high-frequency applications. Theoretical analysis and characteristics of the PSTB converter are presented and verified on a 400-W hardware prototype. The experimental results show that the PSTB converter can achieve a peak efficiency of 90.3% when the switching frequency is 300 kHz. The power density of the PSTB converter is as high as 40 W/in3 with the help of GaN transistors and planar transformers.