Development and validation of model for 95% efficiency, 220 W wireless power transfer over a 30cm air-gap

Although 60 W wireless power transfer was demonstrated in 2007, still there is no equivalent circuit model for a sub-meter air-gap, hundreds of Watts, high efficiency wireless system. A design-oriented circuit model is needed for this technology to evolve. This paper proposes an equivalent circuit model for the wireless system and analyzes the system based on the proposed model. The proposed model and its analysis are validated by means of FEA and experimental results. Furthermore, as a viable solution for high power (over 10 kW) applications, losses in the wireless power transfer system are investigated in the following section. Because of the high operating frequency (MHz), skin- and proximity effect were shown to be dominant. New spatial layout of a coil is proposed that significantly reduces losses caused by skin- and proximity effect. Proposed coil design is evaluated by means of FEA.