1.5-MHz High-Performance 380-V/12-V LLC Resonant Converter

This study proposed a core optimization technique to explore DC-DC converters at a high frequency of 1.5 MHz. In addition, the optimization of the width of PCB winding is proposed by targeting the direct current resistance of the winding; the optimization successfully lowered the conductance loss of the winding under a limited area condition. Conventionally, a winding placement method is applied to a multiple-leg core to achieve magnetic flux offset. A mathematical model was used to describe the effects of additional effective core volume on core loss reduction. In addition, a finite element analysis 3D simulation was used to verify the degree to which additional effective volume reduced core loss. A 1-kW experimental prototype using GaN switches was implemented with an input voltage of 380 V, an output voltage of 12 V, and a power density of 41.1 W/cm
³
. The LLC converter operated at 1.5 MHz with a maximum efficiency of 96.02 %.