A phase shift controlled current-fed Quasi-Switched-Capacitor isolated dc/dc converter with GaN HEMTs for photovoltaic applications

This paper proposes a phase shift controlled isolated dc/dc converter for photovoltaic applications, which is composed of a current-fed half bridge and a Quasi-Switched-Capacitor (QSC) cell. The proposed converter employs phase shift control to realize a wide voltage regulation range, and features zero-voltage-switching on all the switches. Compared to traditional H-bridge and half bridge, the secondary side QSC circuit exhibits a higher boost ratio and reduced voltage stress on devices and transformer. The circuit structure, operation principles and soft-switching analysis of the converter are presented. A 1-kW gallium nitride device based circuit prototype is used to verify the circuit analysis. Both simulation and experimental results are presented.