A novel modular dual-active-bridge (MDAB) dc-dc converter with dc fault ride-through capability for battery energy storage systems

This paper proposes a novel modular dual-active-bridge (DAB) dc-dc converter for spilt-battery energy storage system (BESS) in medium-voltage dc (MVDC) grid application. Compared to modular cascaded DAB converter, the proposed topology has current-fed DAB characteristics, with directly dc current control to achieve dc fault ride-through capability. In addition, the proposed converter exhibits favorite features of DAB converter such as galvanic isolation, soft-switching condition and small passive components. The operating principle is described in details, and the corresponding control system is developed to realize the power flow and balancing control. A case study of 500 kW, 20 kHz BESS based on proposed converter is simulated for validation.