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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.

A key component of the magnetic resonant chargers is the coupler, which must be connected to the compensation networks to improve the power transfer. The design of both structures are tightly related since the configuration of one affects the other. Thus, the integration of both structures is convenient to ease the development of other systems of the wireless charger such as the power converters and control. This integration can be optimized if physical aspects are considered. In this paper, we propose a novel physical integration of circular pads and a LCC-LCC compensation. If both systems are connected without any specific consideration, the inclusion of the reactive components in this high-order compensation network derives in a more bulky-structure. Our proposal consists in implementing the inductors of the compensation networks in the same structure of the power coils, leading to a compact system. The position of the compensation coils must be carefully analysed in order to minimise undesired coupling effects. In the proposed integration approach, we have analysed the coupling coefficients between the magnetic components for several positions to identify the optimised configuration. The feasibility of this compact structure has been validated in a prototype, proving that the power transfer levels are suitable. These tests have been carried out for different misalignment conditions, which could model its performance for dynamic charging.