Examination of Wireless Power Transfer Combined With the Utilization of Distance Detection

Wireless power transfer using magnetic resonant coupling is expected to be widely used in the charging of an electric vehicle and in the use of home electric appliances. Wireless power transfer requires a high efficiency and power transfer over a long distance. However, the efficiency is reduced by the increase of the transmission distance and the change of the impedance of the receiving load. Therefore, a distance sensor using magnetic resonant coupling is proposed. In this paper, we propose a method of power transfer and distance detection using one couple of coils in real time. We also propose to use different frequencies in the power transfer and the distance detection, which are superposed and separated. Using the proposed approach, we demonstrated that the power transfer and the distance detection can be performed without relying on the change of the transmission distance.