Analysis of Assistant Reactive Shielding Coil for Electric Vehicle Wireless Charging System

To realize electromagnetic safety of wireless power transmission (WPT) system for electric vehicle (EV), the shielding methods should be analyzed. This paper proposes a method of using assistant reactive shielding coils to cancel the electromagnetic field (EMF) outside the working area of WPT system. By tuning compensation capacitance of shielding coil automatically, we design 3 cases with different location and shape of coils to achieve reactive shielding. By comparison and simulation, placing ring shielding coils above receiving (Rx) pad and under transmitting (Tx) pad is the best way to suppress EMF of WPT system's non-working area. The shielding coils' radius is slightly bigger than coupling coils' outer radius. This paper also provides a new method to realize WPT shielding system's automatic adjustment for resonance. Besides, assistant reactive shielding coils' cost is lower than traditional aluminum plate.