A 6.78-MHz 2.3-kW Full-Bridge GaN Inverter with Bottom-side Cooled Transistor GS-065-030-2-L for Wireless Power Transfer

Megahertz (MHz) high-frequency wireless power transfer (WPT) system shows advantages in compactness, density, and power transfer freedom. Gallium nitride (GaN) transistors are suited for high-frequency inverter designs due to their extremely high electron mobility and fast switching speed. This paper presents the design, implementation, and experimental evaluation of a 6.78-MHz high-power GaN inverter utilizing the enhancement mode (E-mode) 650V bottom-side cooled power transistor GS-065-030-2-L for wireless power transfer. Thermal dissipation design for GaN transistors, parasitic parameters optimization, and zero-voltage-switching (ZVS) are demonstrated. A 6.78 MHz WPT prototype is set up, and the experimental results demonstrate that the GaN inverter can achieve a maximum output power of 2374 W with ZVS, and the peak DC-DC efficiency of the WPT system achieves 92.88%.