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

Abstract

In this article, a simple and cost-effective symmetric sensing coil set to be used for the metal object detection (MOD) in a stationary wireless electric vehicle charger is newly proposed. Compared to the conventional nonoverlapping 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 MOD based on a sensitivity equation and on the finite element method simulations. An experiment conducted with a metal object 40 × 40 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> in size and a 20 A transmitting (Tx) coil current verifies the reliability and the blind-zone elimination feature of the proposed sensing coil.