Asymmetric Enhanced Wye-Zigzag Transformer for Soft Switching Expansion of Three Phase Dual Active Bridge Operation

Dual active bridge converter (DAB) plays a crucial role as an auxiliary power supply in electric vehicle applications in regulating the input voltage. Owing to the increased momentum toward high-power and high density, the three-phase variant of DAB arises as the key solution to the aforementioned challenge. The key to increased power density is the operation at high frequency and three phase operation. With wide-band gap (WBG) devices and Silicon carbide (SiC) devices, frequency can be hundreds of kilohertz level, which can reduce the transformer volume significantly. In this paper, an asymmetric three phase transformer connection is employed which highlights the importance of partitioning in enhancing the area of soft switching region of the three-phase dual active bridge.