Optimal design methodology for dual active bridge converter under wide voltage variation

Dual active bridge (DAB) converter is a popular topology for bidirectional on-board electric vehicle (EV) charger systems and other energy storage applications. In such systems, wide variation in the battery voltage makes design of the DAB converter non-trivial. The focus of this paper is on the optimal selection of DAB parameters when there is a wide variation in the output voltage. Different optimal strategies based on a minimal Euclidean norm approach, namely `minimal rms current design', `minimal peak current design' and `minimal power loss design' are compared to illustrate the effect on system performance with output voltage variation. The proposed optimal design approaches are shown to be superior to a conventional design approach. A loss model for the DAB converter that can be used in the optimal design process is presented. The proposed optimal strategies are validated with experimental results using a laboratory prototype.