FOREIGN MATTER DETECTION DEVICE, POWER TRANSMISSION DEVICE AND POWER RECEPTION DEVICE FOR WIRELESS POWER TRANSMISSION, AND WIRELESS POWER TRANSMISSION SYSTEM

摘要

A foreign matter detection device detects metallic foreign matter between a first resonator and a second resonator, the second resonator comprising a parallel resonance circuit including a coil and a capacitor. The foreign matter detection device is provided with: the first resonator; an oscillation circuit capable of oscillating at a first frequency (f1) lower than the resonance frequency (fr) of the second resonator and at a second frequency (f2) higher than the resonance frequency (fr); and a measurement circuit for measuring a change in the input impedance of the first resonator. The measurement circuit detects metallic foreign matter between the first resonator and the second resonator on the basis of the change in the input impedance of the first resonator measured by the measurement circuit when the oscillation circuit is oscillating at the first frequency (f1), and the change in the input impedance of the first resonator measured by the measurement circuit when the oscillation circuit is oscillating at the second frequency (f2).