The Optimization of Auxiliary Detection Coil for Metal Object Detection in Wireless Power Transfer

For the safety of customers and WPT Electrical Vehicles (WPTEVs), Metal Object Detection (MOD) is a necessary module in the whole WPT system design. In this paper, auxiliary detection coil which utilizes the influence of metal objects on the detection voltage is used as the method to achieve the MOD and an equation which can optimize the design of MOD auxiliary detection coil is proposed. To optimize the detection coil, approximate quantitative description of voltage change in the detection coil is done by modeling the effect of a metal object. A comparison between the simulation and equation's numerical analysis results is presented that verifies the use of proposed equation. The influence of the radius, turns and position of auxiliary detection coil on voltage variation are also analyzed. And at the end of the paper, the testing result is proposed to verify the feasibility of the optimization method of this auxiliary detection coil design.