Integrated Detection Sensor of Metal and Magnet in Wireless Power Transfer System

This paper addresses the issue of reduced transmission efficiency in wireless charging systems due to foreign metal object and misalignment of coils. It proposes an integrated method for the detection of metals and magnets, which can also enhance the system’s transmission efficiency. First, the theoretical analysis and finite element analysis verify that when a metal and a magnet approach the parallel resonant circuit, the equivalent resistance and inductance of the circuit change, leading to different variations in the quality factor. By detecting the changes in the resonant voltage of the parallel resonant circuit, a distinctive and integrated detection circuit can be designed. Experimental verification shows that the detection device can simultaneously detect magnets and metals, and the output state changes by different output ports. The design of the detection hardware reduces system losses, enhances the cost-effectiveness, and improves the system safety.