Electric vehicles rely on on-board charger converters to charge the battery from the grid when fast dc charging infrastructure is not available. Power density, weight, efficiency, and cost are among the key challenges for these converters, which must operate under a wide range of input and output voltages, as well as in single and multi-phase configurations, leading to costly and suboptimal designs. This paper proposes an optimized on-board charging topology taking advantage of a hybrid dc transformer and dual active bridge topology. The proposed converter achieves both three-phase and single-phase operation without additional elements, soft-switching operation, and a single-transformer design, allowing a high efficiency and cost-effective implementation. Besides, it enables inherent capacitor voltage balancing and fixed frequency operation, allowing a straight-forward control implementation. The proposed converter has been succesfully tested using a 11 kW OBC prototype.
