On-Board Chargers for High-Voltage Electric Vehicle Powertrains: Future Trends and Challenges

The powertrain voltages in battery electric vehicles (BEVs) have witnessed an upward trend due to advantages such as reduced runtime losses and extremely high DC fast charging power levels; aiding in reduced range anxiety and lower battery charging duration. This trend requires original equipment manufacturers (OEMs) to re-assess the design of electronic sub-assemblies (ESAs). Due to newly released DC fast charging standards, there are implications on the on-board charger (OBC), which is one of the ESAs in a BEV. This paper performs a comprehensive review of identifying system-level and use-case related challenges in transitioning on-board chargers to higher voltages compared to state-of-the-art, while considering the impact of newly introduced DC fast charging standards like Megawatt Charging Systems (MCS) and ChaoJi/ CHAdeMO 3.0. The existing research in academia and proof-of-concept designs compatible for high-voltage on-board charging sub-systems, such as the power factor correction (PFC) and isolated DC-DC conversion stages is consolidated. Due to the demand for integration driven by cost-optimization targets, single-stage, traction-integrated, and auxiliary power unit (APU) integrated on-board chargers are discussed. Finally, the disparity between state-of-the-art technology and future requirements is defined to establish challenges and the direction of future research areas.