Split-Capacitor Dual-Active-Bridge Converter

In this article, a split-capacitor (SC) dual-active-bridge (DAB) converter is proposed. In the proposed converter, dc-link capacitors in both the input and output are split, and primary and secondary windings of the transformer are connected to midpoints of the input and output dc links, respectively. Although the switch current stress of the proposed converter is twice that of conventional DAB converter, its switch voltage stress is reduced to half. Therefore, the proposed converter has higher conduction loss than the conventional DAB converter, however, the switching loss can be reduced, which implies that the proposed converter is beneficial and can achieve higher efficiency than the conventional DAB converter as switching frequency increases. In addition, owing to the SC structure, no dc-blocking capacitors are required and the proposed converter can be readily connected to neutral-point-clamped or half-bridge-type converters without increasing the number of dc-link capacitors. To verify the performances of the proposed converter, 3-kW prototypes are built, tested, and compared.