Magnetic field mitigation by multicoil active shielding in electric vehicles equipped with wireless power charging system

A novel design of active coil shielding is proposed to reduce the magnetic field generated by the currents flowing into the coils of a wireless power transfer (WPT) system for charging the batteries of an electric vehicle (EV). The main idea is to divide the traditional active loop used to shield a source in two separate shielding coils so as not to adversely affect the WPT performance. This concept is applied to shield the WPT coils, and, therefore, in the proposed design, there are active coils placed on the ground parallel to the primary coil of the WPT and some others on board below the vehicle, planarly located with the secondary coil. The currents on the active coils are optimized in order to minimize the magnetic field in the most critical zone accessible from humans, i.e., region besides the EV and in the cabin.