2.5-kW power supply unit with semi-bridgeless PFC designed for GaN-HEMT

Wide-gap semiconductors such as SiC and GaN have seen widespread increase in interest as promising materials for use in next-generation power devices. In this paper, we present a 2.5-kW power supply unit (PSU) designed for ICT systems with engineering samples of Fujitsu Semiconductor Ltd. (FSL) 's GaN-HEMTs installed in the power factor collection (PFC) circuit. A new PFC circuit specially designed for GaN-HEMT is proposed: a semi-bridgeless design with a synchronous rectification return line. The bridgeless architecture is suitable for high-power and high-efficiency PSUs, and the synchronous rectification is designed to maximize the GaN-HEMT performance. As the GaN-HEMT does not have a body diode, the return current mainly flows through the return diodes in conventional semi-bridgeless PFCs. By applying synchronous rectifiers instead of return diodes, energy loss in the return line can be reduced to about 1/10. In our experiments, a maximum PSU efficiency of 94.3% was obtained with 230-V AC input and 12-V DC output.