Leakage Current Issue of Non-Isolated Integrated Chargers for Electric Vehicles

Electric vehicle (EV) chargers are traditionally isolated from the grid. Non-isolated chargers have great potential as they enable higher power density at lower cost. Integrated chargers have the potential to utilize existing onboard, high power-rated electronic components for Level 3 charging. Four possible non-isolated integrated charger topologies based on permanent magnet synchronous machine (PMSM) are introduced at the beginning of this paper. Then, the issue of common mode (CM) leakage current through the on-board filters is identified and analyzed. It is found that the leakage current could rise to dangerous levels and cause potential electric shocks to users. The negative influence and safety risks from the leakage current for different grounding systems are also discussed. Experimental results are presented to validate the leakage current analysis. Finally, possible mitigation techniques of the leakage current are discussed.