Comparative Study of Single-phase and Three-phase DAB for EV Charging Application

Bidirectional converters enable vehicle-to-grid (V2G) operations in electric vehicle (EV) charging stations. In this context, dual-active bridge (DAB) DC-DC converter is a preferable solution due to galvanic isolation and reduced volumes compared to other systems. Single-phase DAB (1ph-DAB) and three-phase DAB (3ph-DAB) topologies are usually compared in terms of efficiency and performances with the same rated power. Conversely, this paper focus on a comparison concerning device losses and stresses, medium-frequency transformer (MFT) design and capacitor filter sizing for the same power per switch, considering DABs and batteries coupled in a V2G application. Thereby, the impact of the battery state-of-charge (SoC) variation relative to the grid-side DC voltage is studied. Theoretical analysis and simulations results reveal that, in some respects, 1ph-DAB performance is superior to that of the 3ph-DAB with the proposed comparison approach. While, the main advantage of 3ph-DAB over 1ph-DAB is the reduced size of filter capacitors.