Exploring Switching Limit of SiC Inverter for Multi-kW Multi-MHz Wireless Power Transfer System

Silicon carbide (SiC) MOSFET has significantly facilitated high-power and high-frequency inverter design for wireless power transfer (WPT) systems. However, in the multi-kW multi-MHz area, the application of the SiC full-bridge inverter is still insufficient. This paper aims to explore the switching limit of SiC full-bridge inverter at multi-kW power levels and provides a methodology for MOSFET selection, inverter circuit design, and zero-voltage switching (ZVS) realization. Two sets of inverters are respectively implemented based on isolated gate driver UCC5390 and non-isolated IXRFD631 and tested at a switching frequency of 3MHz similar to 4MHz and an input dc voltage of 350V similar to 550V. The experimental results firstly reveal the potential and capability of a SiC full-bridge inverter in achieving kilowatts high power level at multi-MHz switching frequency with 4.39kW at 3MHz and 3.19kW at 4MHz, and a switching limit of 4MHz is proposed for the SiC full-bridge inverter with overall consideration of ZVS availability and inverter safety.