A Medium-Voltage Transformer with Integrated Leakage Inductance for 10 kV SiC-Based Dual-Active-Bridge Converter

Abstract

Medium-voltage (MV) dual-active-bridge (DAB) converters have become an emerging technology thanks to high-voltage silicon carbide (SiC) devices and nanocrystalline magnetic materials. However, the need of phase-shift inductance and insulation requirements for the MV DAB may complicate the design of the transformer and the MV DAB converter, which can also induce higher loss and occupy more space. In this paper, the leakage integration and insulation techniques are discussed for a 6.7-kV/850-V DAB converter, meeting both the inductance and insulation requirements of the MV DAB converter. Ferrite cores with air gaps are inserted between the LV and MV windings without introducing high loss, and the MV winding is selectively shielded to avoid high parasitics and meet the insulation requirement. Test results have verified the effectiveness of this design.