Design of Reactive Shield Coil for Wireless Charger with Multiple Coils

In wireless power transfer system, a leakage electromagnetic field (EMF) that can affect a human body or peripheral devices is one of the most important problems along with system efficiency. Since ferrite and aluminum which are basically used to reduce the EMF have a high weight and cost, various studies to cancel the EMF using reverse magnetic field by additional coil are being conducted. In this paper, a reactive shield coil that can be applied to a wireless charger with multiple transmitter coils is proposed. The EMF is reduced by applying the proposed coil up to 85%.