Highly Integrated SiC-power Modules for Ultra-Fast Lithium Ion Battery Chargers in LLC-topology

Ultra-fast charging stations for battery electric vehicles can provide a charging power of up to 350 kW and charge 100 kWh batteries in less than 20 minutes. Typically, the charging station comprised several modules connected in parallel to provide the high power. This paper proposes a small and compact SiC LLC converter module compliant to ultra-fast charging demands and capable of delivering 40 kW. The overall system functionality is controlled by an Aurix TriCore microprocessor. As charging stations are expected to operate in a 24h/7d scenario, different power electronic packaging technologies like silver sintering and reliable substrate materials as copper thick-film on Al2O3, bulk copper on Si3N4 have been evaluated. Latest 1200 V, 95 A SiC MOSFETs and rectifying SiC diodes are integrated in an ECONOPack2. A 10 kWh air cooled module is compared to an immersion cooled system with an output power of 40 kWh by CFD simulation. Simulation results reveal, that the immersion cooled system can easily handle the thermal losses and hence, a reliable, highly integrated ultra-fast LLC charging system can be realized.