Introduction of spiral coils in wireless charging which enables magnetic field suppression at foreign object location

The primary drawback of wireless power transfer (WPT) systems that are used for electric vehicles (EVs) in parking lots is the abnormal heat generation caused by the absorption of magnetic fields by metallic foreign bodies. This paper presents a phased-array wireless power transfer method that suppresses the magnetic field around a metallic object for seamless power transfer. In this approach, it is assumed that the object exists at an arbitrary point on a two-dimensional plane. However, helical coils were used in previous systems, and this increased the physical size of the WPT system, specifically when the coils were arranged in an overlapping configuration. Therefore, in this paper, spiral coils are introduced to make the system compact. Simulation results confirmed that the magnetic field suppression was sufficient.