Electromagnetic analysis of coils for wireless power transfer

The accurate modelling of a system a coupled coils is of paramount importance in the design of wireless power system. In particular, the resistances of the coils and their mutual inductance coefficient determined the efficiency of the device. In this contribution the authors compare the parameters of a two coils system obtained by two numerical codes with the corresponding experimental data. One of the numerical codes is COMSOL, the other is a research code developed at DESTEC. Comparison was performed on a wide frequency range where the skin effect on the current density distribution inside the conductor assumes a relevant importance. The measured system is part of a prototype of a hybrid WPT - PLC system, and the measurements of the scattering parameters have been taken in the frequency range from 30kHz to 30MHz by the use of a VNA. The simulations performed show that the high frequency behaviour of coils made by 'thick' conductors is a difficult task and different codes are characterized by different performances.