A novel winding layout strategy for planar transformer applicable to high frequency high power DC-DC converters

High power isolated full bridge DC/DC converters are used widely in electric vehicles (EVs) and hybrid electric vehicles for battery charging purpose. Such DC/DC converters use planar magnetic components to minimize their size and weight and to increase their ability to withstand mechanical vibrations. Typical planar transformers (PT) in DC/DC converters have high inter-turn and inter-layer capacitances that cause them to draw high peak currents, increase voltage overshoot across secondary rectifying devices, and increase leakage current, which causes EMI problems. These key problems of PT restricts increase of switching frequency of DC/DC converters used in EVs, which in prevents designers of such DC/DC converters from decreasing overall size and weight of the converters. This paper proposes a novel winding layout strategy to mitigate the stray capacitance of planar transformers. The effectiveness of the proposed winding strategy is validated by analytical and experimental results that are presented in the paper.