Design of A 50-kW Medium Frequency Medium Voltage Transformer for 10-kV SiC-Based Dual Active Bridge Converter

In this paper, a 50-kW 1-kV/6.25-kV medium voltage dual-active-bridge (DAB) transformer has been designed and tested. The shell-type transformer structure with stacked small cores is selected to integrate the leakage inductance and reduce the eddy current loss. Dry-type insulation with selective shielding is adopted and both winding-to-ground and winding turn-to-turn insulation are considered. The transformer geometry-based design procedure is discussed to achieve high efficiency and power density considering the effect of eddy current loss and insulation constraint. Tests up to the full voltage and power were performed and the DAB transformer achieved 99.66% full-load efficiency and 13.5 kW/L density for the transformer.