Effective Electrical Model of a Beverage Can as a Foreign Object in EV Wireless Charging

Wireless chargers for electric vehicles are usually based on a magnetic field between two coils to transfer power without cables. Metallic objects in the volume comprised among these coils affect the magnetic field, reduce the power transferred to the load, and also result in hazards. Therefore, the implementation of techniques suitable to detect foreign objects is mandatory. The accurate modelling of the objects can help in the precision of the methods used for their detection. In this paper, we accurately identify the equivalent electrical model of a specific foreign object. The main advantage of using this model consists of the possibility of evaluating the performance of the whole charging system by performing time-domain simulations instead of complex finite element analysis. This is of interest for techniques using sensing coils and for self-sensing approaches. In particular, we have modelled a beverage can, which is an object expected in typical EV wireless chargers. The model is validated by comparing simulations based on this model and experimental results. From this analysis, some hot areas where the object causes a higher impact are identified. The procedure can be extended to other objects.