Analysis and Design of a 1-MHz Bidirectional Multi-CLLC Resonant DC-DC Converter With GaN Devices

A 1-MHz half-bridge high-gain multi-CLLC bidirectional resonant converter with (gallium nitride) GaN field effect transistor (FETs) and integrated planar magnetics is proposed in this paper. It presents excellent gain characteristic and high power density, which is very suitable for a distributed energy storage system. The operation principle, topology features, and parameter design method of the converter are discussed in detail. The improved winding method of integrated planar magnetics is also elaborated. And then, a 400-W prototype is established and the corresponding experiments are carried out in 1 MHz. Finally, the accuracy and correctness of the theory are verified and the highest efficiency of the converter can reach 94.3%.