Design and optimization of magnetic resonance coupling by using relay effect

Wireless power transfer (WPT) is a device that transmits electrical energy from a power unit to an electrical load through the air wirelessly or without the interconnection of any conductors. The designs of current WPT are quite large and inappropriate for many applications, especially for electronic devices. The small scale (mid-range WPT) with 1 meter distance was investigated to develop a wirelessly transmitted energy for the use of electronic devices, particularly to charge portable devices. The distance of a mid-range WPT can be increased by placing the resonators between the transmitter and receiver to achieve the 1-meter distance of the WPT. The power transfer efficiency (PTE) was significantly enhanced when the resonators was placed. The high efficiency was maintained due to the increasing distance of the WPT. As a result, more power can be transmitted from transmitter to the receiver respectively.