A Method for Suppressing Leakage Current of Non-isolated Integrated On-board EV Battery Charger

The integrated on-board battery chargers (IOBCs) can repurpose existing high-rated power electronic devices in the electric vehicle (EV) for charging, aiming to cut costs. However, non-isolated IOBCs face significant common-mode (CM) leakage currents due to the lack of current isolation and coupling between the ac and dc side CM filters. This paper introduces a technique that combines topology and modulation to suppress CM leakage currents in a non-isolated integrated charger. The touch current can be suppressed below a reaction threshold of 1 MIU. This enhancement enables the safe use and commercialization of transformer-less chargers, making superior charger efficiency, power density, and cost-effectiveness achievable. The CM model of the system is derived to guide the design of circuit topology and modulation schemes. The simulation results are used in the feasibility discussion of these techniques. Finally, a prototype of a 6.6 kW experimental charger is proposed, and experimental results demonstrate the effectiveness of the proposed solution.