A Multi-Port Converter as an Onboard Electric Vehicle Charger: Enabling 800V Battery Charging from 400V EVSE

Electric vehicles (EVs) face challenges in reducing the charging time and managing the power efficiently. Increasing the charging power can significantly reduce the charging time for the EVs. Current DC fast chargers operate at tens to few hundreds of k W which is insufficient to achieve charging times equivalent to conventional refueling. Advancing to ultra-fast charging above 500kW requires higher battery voltages, such as 800V, to reduce current and hence, the conduction losses. However, compatibility issues arise with existing 400V charging stations, necessitating a power electronic converter to boost the voltage. This paper analyzes the Dual-Transformer Triple Active Bridge (DT-TAB) as an onboard multi-port converter solution. The DT-TAB topology, an extension of the Dual Active Bridge, utilizes two transformers to mitigate power coupling issues and achieves zero-voltage switching (ZVS) across wide voltage ranges, minimizing switching losses. This study focuses on the design, simulation, and closed-loop control of a 22kW DT-TAB implementation, resolving the charging compatibility issue for present EVs.