A review of foreign object detection (FOD) for inductive power transfer systems

Abstract Wireless power transfer (WPT) has a promising application prospect due to its convenience and feasibility to special occasions. Inductive power transfer (IPT) uses the magnetic field for power transfer and it is currently the most popular and mature WPT technology. However, the strong magnetic field will heat up metal objects falling in the charging area due to eddy currents generated in the objects. It can also harm animals or toddlers staying in the charging area. To deal with these issues, foreign object detection (FOD), including metal object detection (MOD) and living object detection (LOD), should be developed for the safe operation of IPT systems. FOD can be divided into system parameter detection methods, wave-based detection methods, and field-based detection methods. System parameter detection methods are normally used in low-power systems for MOD. Wave-based detection methods are suitable for high-power applications, for both MOD and LOD. Field-based detection methods work for both high-power and low-power applications, for both MOD (in an inductive way) and LOD (in a capacitive way). This paper reviews and summarizes the state-of-the-art development of FOD technology in IPT systems.