On-Demand Battery Reconfiguration for 800V DC Fast Charging in Electric Vehicles

With huge lineup of EVs to be released in the market by MY2030, fast charging is becoming a big differentiator between electric vehicle (EV) offerings. EVs with 400V batteries can’t use 350kW Ultra-Fast DC Chargers at 800V, leading to longer charging time. This paper describes a battery architecture that achieves ultra-fast DC charging of a rechargeable energy storage system (RESS) to reduce the charging time of a 400V EV by half. The concept uses novel reconfigurable battery scheme with low loss switching circuit for transitioning between normal 400V propulsion-mode and 800V fast-charging on-demand. It enables faster charge on-demand for customer, enabling use of emerging 800V DC fast charger without putting extra cost of reengineering the entire EV propulsion system for 800V to get the fast-charging advantage. The paper details the architecture, the switching circuit design, the simulation results and experimental tests done showing feasibility in hardware.