Resonant Reactive Current Shield Design in WPT Systems for Charging EVs

In this paper, the resonant reactive current shield is introduced. The wireless power transfer (WPT) system model is analyzed as equivalent lumped circuit parameters. Controlling the shield impedance magnitude and phase are established. Two positions for the resonant reactive current loops are proposed, when (1) shielding loops are in the same level with the WPT coils, and (2) above the receiving (Rx) and under the transmitting (Tx) ferrite cores where the shielding loops radius are bigger than the WPT coils radius for both positions. Finite element method (FEM) software is used for evaluating the electromagnetic field (EMF) surrounding the charger for the two proposed positions. The simulation results show that the first position design is succeeding to reduce the EMF in X-axis and Z-axis. The proposed system can transfer 5 kW, 15 cm air gap with slim and comfortable WPT pads.