Inner-Field Guiding Resonator for Efficient Wireless Power Transmission in Proximity Charging Condition

An inner-field guiding resonator (IFGR) is presented for efficient wireless power transmission (WPT) using resonant inductive coupling in proximity charging condition. The IFGR is inserted into a source resonator to obtain a uniform magnetic field distribution which is the important design factor of a proximity WPT system, because it makes the system simple without an adaptive matching technology. As the location of the target resonator changes, the transmission efficiencies are simulated and measured to validate uniform- and high-transmission efficiency. To optimize the WPT system using the IFGR, the design procedure is proposed. Considering the practical WPT system with ground plane, the proximity WPT system including one or two mobile devices was designed and fabricated. The average of the total efficiency at all positions on the source resonator was measured as 82.9% (one mobile device) and 87.1% (two mobile devices), respectively. These results prove that an efficient proximity WPT system can be successfully designed using the IFGR.