A planar positioning-free magnetically-coupled resonant wireless power transfer

A novel magnetically-coupled resonant wireless power transfer (MCR-WPT) system using an array of printed spiral coil (PSC) resonators is presented to expand the receiving area. The resonator array is excited with a single planar driving loop to yield uniform magnetic field distribution at the receiver plane. First, the performance of a conventional transmitter coil array consisting of one transmitting resonator and multiple repeaters without frequency tracking is investigated. Then the performance of the proposed PSC resonator array with novel feed strategy is demonstrated. The results show the proposed MCR-WPT array system is able to provide consistent transfer efficiency when the receiver is axially misaligned with the transmitter. The measurement results are compared with the conventional planar MCR-WPT array and reveal that that with the proposed design, the transfer efficiency of the planar MCR-WPT system can be increased from 2.1% to 65.8% in the misalignment region.