Next Generation of High Power Density On-Board Chargers for Electric Vehicle Systems

Electric vehicles are becoming increasingly popular, which has led to higher demands for on-board chargers (OBCs) that have to be compact, efficient, and compatible with different power systems worldwide. Currently, the state-of-the-art solution involves a phase-modular design, but this has limitations in terms of achievable power density due to the large number of components required. To achieve higher power density, the next generation of OBCs are transitioning to true three-phase topologies like the B6/B8 topology, which use 1200V-rated SiC MOSFETs. Additionally, multi-level topologies employing 600V-rated GaN HEMTs have been identified as a way to achieve further improvements in power density. This paper shows two possible options for future OBCs to achieve the next level of power density: Non-isolated OBCs and single-stage power conversion enabled by monolithic bi-directional GaN HEMTs. These two different approaches are evaluated with respect to the single- and three-phase power processing requirements for worldwide compatibility, as well as the upcoming trend towards bi-directional power flow capability for V2x applications.