Design Optimization of High Frequency Transformer for Resonant DC/DC Converter

Resonant DC/DC converter is extensively applied in the industry due to their superiorities such as zero voltage switching which enables it to operate under higher frequency. As the core component of resonant DC/DC converter, the high-frequency transformer (HFT) is critical to the performance of the converter in regard of power density, efficiency, and reliability. However, as the frequency and power rating increase, the power loss on the wire and core increase as well. It is desired to propose the optimal design process for integrated HFT which considers the tradeoff between volume and power. This paper comprehensively investigates the impact of air gap length, location and winding structure on the transformer. Based on the analytical model, the design flow of a magnetics integrated transformer which incorporates intrinsic magnetizing inductance and leakage inductance for the resonant tank is presented. Finally, the analytical model and the optimization design of HFT are validated with experimental results.