Optimal Wireless Power Transfer to Systems in an Enclosed Resonant Cavity

This letter describes the development and implementation of an impedance-matching (IM) method for achieving optimal power transfer efficiencies (PTE's) in cavity resonator wireless power transfer (WPT) systems. Specifically, we develop a bandpass filter (BPF) circuit model and utilize network analysis to predict and realize maximum achievable PTE to miniature systems enclosed within a hollow metallic cylindrical cavity excited in TM010 resonant mode. Measured PTE results are demonstrated matching closely with the developed theory and circuit simulations. We achieve a peak PTE of 33% to a 5-mm-diameter receive coil that occupies a volume that is 5.23 x 10(6) times smaller than the volume of the cylindrical cavity. Our achieved PTE is 4 times larger than the PTE achieved to a system with no optimal IM network but only a single resonant capacitor connected in series with the receive coil. The model and results presented illustrate our optimal design methodology for realizing maximum achievable PTE in cavity resonator WPT systems.