A High-Efficiency 1 MHz 65 W GaN-Based LLC Resonant DC-DC Converter

This paper presents an LLC resonant DC-DC converter for single-phase offline converters. A 1 MHz 400 V to 48 V prototype employing gallium nitride (GaN) switching devices is designed and implemented. A high-frequency magnetic material is used for the magnetic devices, with the resonant inductor integrated in the transformer. The converter operation is based on soft switching and achieves up to 65 W of output power with a peak efficiency of 96 % at full-load. Inherent load regulation capability is demonstrated from 5 to 65 W of power with fixed switching frequency, while line regulation for 360 to 440 V input is verified with a frequency modulation range of 816 to 1256 kHz respectively.