Impact of Foreign Objects on Wireless Power Transfer Efficiency in Magnetic Coupling Systems

Inductive wireless charging has emerged as a viable solution for charging electric vehicles (EVs) both in stationary mode and on the go, i.e., dynamic charging. EVs are produced at a commercial level, and their wired charging stations are widely available. However, challenges still restrict the development of wireless charging infrastructure on a commercial scale. One significant challenge is the presence of foreign objects on the magnetic coupler surface. Although several foreign object detection (FOD) methods exist, the implementation of each method is cost-dependent. Among these methods, the parametric detection method is considered the most cost-effective. However, the effective precision of this method is still debatable. In this article, the performance of the magnetic coupler is analyzed under the influence of different materials as foreign objects. The analysis presented in this article is threefold. Firstly, a mathematical model of the magnetic coupler in the presence of a foreign object is developed. Secondly, the effect of different materials is analyzed as a function of coil parameters, including inductance, resistance, and coil losses. Lastly, the magnetic field distribution and magnitude are studied using finite element analysis (FEA). The influence of these materials is ultimately evaluated in terms of output power losses and efficiency. The study concludes that the presence of aluminium as a foreign object is responsible for significant power losses in the wireless power transfer system.