Modular Multiport Electric-Vehicle DC Fast-Charge Station Assisted by a Dynamically Reconfigurable Stationary Battery

Multiport battery-assisted dc fast charger (BA-DCFC) stations enable high charge rates of electric vehicles (EVs) at sites that have insufficient grid capacity. However, BA-DCFCs are expensive and inefficient due to the battery energy storage system (BESS) and high-power isolated dc–dc converters that interface the BESS and EV charging ports. This article presents a modular multiport dc linear fast charger (LFC) for EVs, which uses a stationary, reconfigurable battery energy storage system (rBESS), a current-mode, digitally controlled bidirectional linear regulator (LR), and a contactor matrix. The LFC LR increases the overall station efficiency and eliminates the volume and cooling complexity associated with the high-power magnetics, high-voltage capacitors, and high-frequency switches of state-of-the-art (SotA) isolated dc–dc converters. Compared to a SotA isolated dc–dc converter, the LR experiences 83.6% less loss for the same rated EV charge power. Over a day of typical operation, a three-port LFC station is shown to have 28% less loss than a state-of-the-art BA-DCFC, with an average efficiency of 93.4%. The LFC achieves redundancy at the station, BESS, and LR levels while also integrating active balancing of state-of-charge/health without auxiliary switched-mode converters. The proposed system is verified using full-scale transient simulations and experimental results from a scaled, hardware-in-loop implementation with a custom LR and series-connected battery modules.