Foreign Object Detection in Wireless Power Transfer Using Sensing Coils

If charging coils are buried under the parking lot and electric vehicle (EV) can be charged anywhere it was parked, it would be a great advantage for EV drivers. However, the possibility that foreign object exists between transmitter (Tx) and receiver (Rx) coils would be a potential hazard to such wireless power transfer (WPT). Electric signals such as inductance, current or output power can be used to perceive the existence of the object. But size or location of the object still cannot be known, so it is difficult to estimate the degree of risk. Plus, the possibility of misalignment also makes it difficult to determine which of the two situations. Therefore, we analyze the magnetic field distribution using sensing coils on the Tx side. In this paper, Finite Element Analysis (FEA) simulation and experiment for WPT system were conducted in terms of electrical parameters and magnetic field distributions.