The Hybrid Transformer With Battery Storage Integration for Electrical Vehicle Ultrafast Charging

Abstract

Integrating battery storage (BS) in an electrical vehicle (EV) charging station can mitigate the impacts on the grid and enhance the charging capacity. A hybrid transformer (HT) featuring the partial power processing (PPP) function, multiplexing of converter unit, and coordination with ac grids is proposed with BS integration for ultrafast charging station (UFCS). The proposed circuit and the operational fundamentals are introduced first. Parameter design and performance analysis are then discussed. Compared with the typical configurations, the total converter capacity to obtain a defined charging capacity is significantly reduced. The efficiency of HT is enhanced because of the PPP effect and straightforward configuration. Calculations, simulations, and experiments are completed and compared to verify the improvement. The highest efficiency of a 200-kW HT setup reaches up to 98.2%, even higher than the highest converter unit efficiency of 98%. The total converter capacity, which is only 396 kW to achieve a maximum of 380-kW power conversion, is much less than that of the other configurations. Moreover, the rate and amplitude of ac power change are significantly mitigated in a charging station, where the charging capacity is highly improved by the BS integration.