Wireless Power Transfer System for Mobile Robots with Impedance Matching by Adjusting Position of Driver Coil
Toshiki OHORI, Xiang Li, Hideyuki Nakanishi, Shigeki Ozawa, Wataru Hijikata
Abstract
Wireless power transfer based on magnetic resonant coupling can be used to supply power to a mobile robot within a few meters of a transmitter coil. However, when the robot moves or its power consumption fluctuates, its input impedance varies significantly and, in case of impedance mismatch, power reflection may occur. To address this issue, we employed a driver coil on the transmitter side to match input impedance. By regulating the coupling coefficient between the driver and the transmitter coils, the input impedance is matched and power reflection is eliminated. Input impedance regulation is achieved by moving the driver coil mechanically. As confirmed by our experiments, the transmitting efficiency matched with the analytically calculated value, and the input impedance was matched for a vast range of distances from 0 to 1 m and load resistances from 4 to 210 Ω by moving the driver coil properly. Therefore, the proposed system successfully addresses the power reflection problem in wireless power transfer for mobile robots.