Omnidirectional wireless power transfer system supporting mobile devices

The growth in the use of implanted medical devices, mobile devices and electric vehicles is exciting interest in wireless power transfer system. Wireless power transfer system (WPT) via magnetic resonant coupling was firstly proposed in 2007, and the system can transfer power to the receiving device over a distance of several times of the radius of the coils [1]. The WPT is not sensitive to the biological and other environmental objects for the E/H ratio is strongly suppressed in the near field of magnetic dipole and has been shown to be a promising technology for mobile wireless charging. The issue that the transmission efficiency drops rapidly as the transmission distance is increasing has been studied. Nevertheless, the efficiency is sensitive to not only transmission distance but also the relative position between the transmitting coil and receiving coil, and this limit the mobility of device. Although several techniques such as array of resonators, transponder-based system, and spatially structured resonant coil have been studied to obtain mobile WPT [2-4], mobile WPT has still been a problem when the relative angle between the receiving coil and transmitting coil (receiving angle) is increasing. In this paper, an efficient method for the design of omnidirectional wireless power transfer (OWPT) will be proposed.