Enhanced Phase Shift Segmentation Modulation for Soft-Switching in MV DAB Converter Using Series-Connected SiC MOSFETs

The dual active bridge converter using series-connected SiC
mosfet
s (S-SiC) has attracted considerable interest in medium voltage power conversion. However, under certain operating conditions, S-SiC tends to lose zero voltage switching-
on
(ZVS-
on
), which severely impacts the converter's efficiency and S-SiC's reliability. This article proposes an enhanced phase shift segmentation modulation (EPSS) to achieve ZVS-
on
of S-SiC over a wide range of voltage ratio and transmission power. The foundation of this work lies in the analysis of the soft-switching boundary, which uncovers the auxiliary soft-switching effect linked to the magnetizing current and voltage ratio. This insight facilitates the derivation of an equivalent voltage ratio, simplifying parameter design. Furthermore, phase shift ratio combinations are expanded based on soft-switching boundaries to propose EPSS. A rigorous analysis of operational modes and characteristics reveals that EPSS can achieve a significant reduction in S-SiC loss with limited low voltage (LV) side arm loss incurred. Finally, experiments validate EPSS's effectiveness in achieving soft-switching and enhancing overall efficiency.