Optimization of key power loss for LLC circuits with planar transformer in high-frequency and high-power scenarios

An accurate power loss model, for the design of high-efficiency switching power supplies, is difficult to establish due to the complicated magnetic components where the power loss is hard to calculate. This paper proposed a multi-level power loss model of LLC circuits with a planar transformer of high frequency, high power, and low voltage output. The key loss items can be optimized by using this loss model, the accuracy of which and the feasibility of the optimization method are validated by extensive prototype experiments. The experimental results show that the average accuracy of the loss calculation is about 93.6%, and the high efficiency at high-power conversion (95.9% @ 3 kW, 224–16 V) has been realized using an optimized prototype converter.