Modified mu-zero resonator for efficient wireless power transfer

A mu-zero resonator with an effective zero permeability is presented for efficient wireless power transfer (WPT) using resonant inductive coupling (RIC). An N-cell mu-zero resonator is modified to maintain a fixed size and resonance frequencies that are important design factors of WPT using RIC because they are related to the magnetic coupling coefficient and Q-factor. The resonator has many resonant modes with the extraordinary phenomena of metamaterials such as an infinite wavelength wave and backward-wave propagation. An analysis of the resonant modes and a design of the N-cell mu-zero resonator is performed by theory and full-wave simulation based on a dispersion diagram and magnetic field distribution. The power transfer efficiencies of one-cell and two-cell mu-zero resonators are simulated and measured. To optimise the transfer efficiency of the WPT system using the mu-zero resonance (MZR) mode, which supports stronger coupling than the other modes, an equivalent circuit of mu-zero resonator is analysed for a high Q-factor. The theoretical, simulated, and measured results of a one-cell resonator with optimum values confirm that an efficient WPT system can be successfully designed by the MZR mode.