Design of a Resonant Reactive Shield With Double Coils and a Phase Shifter for Wireless Charging of Electric Vehicles

In this paper, a novel resonant reactive shield using a double-shield coil and phase-shift circuit is proposed to reduce magnetic field leakage in electric vehicle wireless charging applications. The double-reactive shield with a four-capacitor phase shifter generates a canceling magnetic field, the phase of which is perfectly opposite to that of the incident magnetic field, effectively reducing the leakage magnetic field as a result. The concept and structure, and an equivalent-circuit model analysis of the double-reactive shield are explained and discussed. The shielding effectiveness of the double-reactive shield is compared with that of a conventional reactive shield with a single-shield coil by a simulation and is verified by experiments.