Symmetric Sensing Coil Design for the Blind-zone Free Metal Object Detection of a Stationary Wireless Electric Vehicles Charger

Abstract

In this paper, a simple and cost-effective symmetric sensing coil set to be used for metal object detection (MOD) in a stationary wireless electric vehicle charger is newly proposed. Compared to the conventional non-overlapping sensing coil using the magnetic field change detection method, the proposed symmetric sensing coil set design offers the considerable advantage of eliminating all blind zones, i.e., regions where metal is undetectable in the conventional method. Moreover, by reducing the number of layers to one, the fabrication of the proposed sensing coil is easier and more cost-effective. The design of the proposed sensing coil is optimized for highly sensitive metal object detection based on a sensitivity equation and on finite element method simulations. An experiment conducted with a metal object 40x40mm2 in size and a 20A transmitting (Tx) coil current verifies the reliability and blind-zone elimination feature of the proposed sensing coil.