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Detailed theoretical and numerical analysis reveals that Witricity, which was first reported by a research team at the Massachusetts Institute of Technology, is efficient and practical for mid-range wireless energy exchange to transmit nontrivial amount of power wirelessly over a long distance. This paper presents an analytical model, based on Witricity technology, for resonant magnetic coupling to address misalignments between the transmitter and receiver of this advanced system. The relationships among the energy transfer efficiency and several key parameters of the system are analyzed using finite element method (FEM). Formulae are derived for the magnetic field of the receiver coil when it is laterally and angularly misaligned from the transmitter. A resonant near-field power transfer formula is suggested to incorporate the coil characteristics and misalignments. Experiments have also been carried out to facilitate quantitative comparison. It is shown that a maximum degree of misalignment can be defined in a given application. The analysis reported allows a formal design procedure to be established for the optimization of Witricity for a given application.
Date of Publication: Oct. 2011