Converter Topology Comparison for a Two-Stage Level-2 Onboard Charger in 800-V EV Powertrains

Abstract

The operating voltage of powertrains in Battery Electric Vehicles (BEVs) has witnessed an upward trend due to advantages in ultra-fast charging and reduction in run-time losses due to lower operating currents in the powertrain. Original Equipment Manufacturers (OEMs) such as Porsche, Audi, and Lucid Motors have introduced vehicles with powertrains operating from 800 V to 924 V. Due to increased switching losses at these voltage levels, the operation of DC-DC converters requires cascading of existing topologies or a multi-level operation. With increasing battery sizes, traditional Level-2 3.3 kW on-board chargers (OBCs) are deemed insufficient to fully complete a charge overnight. Thus, due to increasing voltage and power levels in commercial BEVs, this paper investigates the Grid to Vehicle (G2V) mode’s priority operating regions for a 11.5 kW Level-2 on-board charger in context of an 800 V powertrain. A design procedure for three potential DC-DC converter configurations is performed, and an optimization process is established. A multi-domain comparison highlighting the cost, advantages, and disadvantages of each configuration has been presented.