A 120kW Symmetrical Multi-Winding Split Planar Transformer for High-Power High-Efficiency Isolated DC-DC Applications

In this paper, a 120kW symmetrical multi-winding split planar transformer (SMWSPT) based on ferrite cores is proposed for high-power high-efficiency isolated DC-DC applications. A novel multi-winding structure based on the Archimedes spiral is employed, so a symmetrical multi-wingding structure is realized. Consequently, the proposed winding structure not only boosts the power rating of the split planar transformers but also provides a good current sharing among the windings. Meanwhile, the proposed multi-winding structure permits the application of distributed compensation capacitors and connects each of the windings to the paralleling converters, avoiding the directly parallel connections of the SiC-MOSFETs within the power converter and the associated current sharing issues. The operating principles and the analytical model of the proposed SMWSPT are presented and investigated in detail. Finally, a 120kW SMWSPT prototype is built and tested on a 39kHz CLLC converter. The peak efficiency of the CLLC converter is about 99.310%, and the efficiency at the full load of 120kW is about 99.137%. The power density of the proposed SMWSPT is 24.90kW/L. This paper shows for the first time that the split planar transformer can achieve the power up to 120kW with high efficiency and high-power density.