Analysis and Design Considerations of a Contactless Magnetic Plug for Charging Electric Vehicles Directly From the Medium-Voltage DC Grid With Arc Flash Mitigation

Electric vehicle charging has shifted to higher voltages to achieve higher power for more rapid charging capabilities. This article provides a contactless magnetic plug solution that enables medium-voltage grid connections for electric vehicle charging to achieve 3.5-kVDC-to-400-VDC, 150-kW rapid charging capabilities. This novel magnetic plug improves upon existing electric vehicle charging solutions by guaranteeing safe operation and connection through galvanic and physical separation from the medium-voltage side. It achieves this with a gap and barrier in the transformer core. We introduce a unique asymmetry in the core to localize parasitic capacitance, fully separating the medium- and low-voltage regions. This approach eliminates arcing risk and allows rapid charging capabilities to be delivered to the general public. This gapped core constitutes the plug action of our proposed charging system. We present solutions for the unique challenges of this solution through a detailed analysis of the magnetic design. We confirm this analysis in finite-element analysis and experimentation. The solution is verified through a scaled laboratory prototype of 20 kW, 1 kVDC to 50 VDC that is representative of the proposed 150-kW design. We demonstrate safe, arc-free, disconnection in included active content, a new solution for high-power electric vehicle rapid charging.