Half-bridge LLC resonant converter design with GaN HEMT

LLC resonant converter is concerned for its inherent soft switching features. What's more, Gallium Nitride high electron mobility transistors (GaN HEMT) has smaller on-state resistor and much smaller gate charge and junction capacitors compared with the silicon MOSFET. In this paper, a LLC resonant converter with high efficiency based on 600V GaN HEMT is presented. Controller design procedure is discussed based on its transfer function model that is derived from extended describing function (EDF) method. A 240W, 380V to 12V LLC converter using GaN transistors is demonstrated in this paper which achieves more than 93% efficiency without Synchronous Rectifier. Experiment results are provided to validate theoretical design and analysis.