Continuously Tunable Impedance Matching System in Wireless Power Transfer via Magnetic Resonant Coupling with Soft Magnetic Materials for Autonomous Mobile Robots

Abstract

Wireless power transfer via magnetic resonant coupling can supply power to a robot located several meters away from a transmitter coil. However, when the distance between the transmitter coil and the robot or power consumption of the robot is changed, the input impedance varies and causes power reflection. Then we propose an impedance matching system using a driver coil and soft magnetic material. We apply bias magnetic field to soft ferrite to control path of magnetic flux generated by driver coil actively, and the coupling coefficient between the driver coil and the transmitter coil changes to match impedance. The result of experiment showed that input impedance could be changed by using bias coil.