Patent ID: 9058928
Filing Date: 2015-06-16
Classification: H01F,H02J,H04M

Abstract:
1. A wireless power feeder comprising: a feeding coil, to which no capacitor is connected, is magnetically coupled to a receiving coil; a power transmission control circuit that supplies AC power at a drive frequency to the feeding coil and controls the drive frequency; and a phase detection circuit that detects the phase difference between voltage and current phases of the AC power, wherein the feeding coil forms a resonance circuit together with the receiving coil and a capacitor connected to the receiving coil, the feeling coil and the receiving coil are disposed in a relative position so that a resonance frequency of the resonance circuit changes based on a change in the relative position, and the power transmission control circuit adjusts the drive frequency so as to reduce the detected phase difference which changes in response to a change in the resonance frequency.