MHz LLC Resonant Converter Design with GaN HEMT

With the rapid development of new energy technology, telecommunication technology, and big data centre, the power density and conversion efficiency of the power supply have put forward higher requirements. Gallium nitride (GaN) devices are characterised by high switching speed, low on-resistance, and no reverse recovery loss; LLC converters have become one of the most popular isolated high-efficiency DC-DC converter topologies with their unique soft-switching characteristics, and so they have been widely used in various scenarios. In this paper, a $350 \sim 400 \mathrm{~V}$ to 48 V LLC prototype is built based on a half-bridge LLC topology using GaN HEMTs as primary power tubes, combined with planar transformer technology and synchronous rectification in order to minimise the switching losses of the LLC resonant converter at high MHz frequencies. The converter achieves a peak efficiency of 95.58% and a full load efficiency of 93.74%, which is experimentally verified to be the correct design solution.