Design of a shielding coil for fiber composite electric vehicles with a SAE J2954 WPT system

This work deals with the mitigation of magnetic field levels produced by an automotive wireless power transfer (WPT) system. For this purpose, a 1-turn passive shielding coil is adopted, positioned on the underneath of the vehicle, around the receiving coil and terminated on a tuning capacitor. The design of an efficient shielding coil is detailed in terms of dimensions, shape, and position, along with a methodology for selecting an optimal terminal capacitance. The shielding effectiveness (SE) during stationary wireless charging of an electric city car with a carbon fiber reinforced polymer (CFRP) chassis is calculated numerically. The proposed mitigation technique allows compliance with the limits set for electromagnetic field (EMF) safety and demonstrates how a correct design of a shielding coil does not degrade WPT system performance.