A Fast Charging Station for Electric Vehicles with 400-V/800-V Charging Ports and Second-Life Batteries

Long charging times and Li-ion battery disposal are well-known issues concerning battery electric vehicles. To cope with the first, developing ultra-fast charging stations with a stationary storage system is possible. For the second issue, end-of-life batteries from the automotive industry, referred to as second-life batteries, can be used in grid applications to extend their life cycle. However, integrating different second-life batteries can be difficult due to their different technologies. In this scenario, this paper proposes an ultra-fast charging station topology based on a modular multilevel converter providing 400-V and 800-V charging levels with the capability to use second-life batteries as power buffer. The proposed charging station is capable of managing them solely through the internal circulating currents of the converter. Criteria and guidelines to properly evaluate the battery management effectiveness and to select battery capacities are derived, discussed, and validated through simulations.