Multi-thread sensing coil design for metal object detection of wireless power transfer systems

Metal object detection (MOD) is imperative for a wireless power transfer (WPT) system to ensure operating safety and reliability. In this paper, a MOD approach based on multi-thread sensing coils is newly proposed. First, the principle of the conventional even sensing coil together with its limitation in position-dependent detection sensitivity is analyzed and validated by simulation. Then, the coil turns of each thread and distance between two adjacent threads of the proposed multi-thread sensing coil are optimized to obtain evenly induced voltage regardless of the position of the metal object on the sensing coil. Finally, a MOD prototype with the proposed multi-thread sensing coil is established and compared with even sensing coils. The simulation and experimental results show that the multi-thread sensing coil proposed in this paper can improve the uniformity of the voltage difference at different detection positions by 68% compared with the conventional even sensing coil.

Automated summary

A metal object detection (MOD) approach based on multi-thread sensing coils is proposed in this paper, optimizing coil turns and distance between threads to improve voltage uniformity at different detection positions. Simulation and experimental results demonstrate a 68% improvement in voltage uniformity compared to conventional even sensing coils.