Patent ID: 8829726
Filing Date: 2014-09-09
Classification: H02J

Abstract:
1. A wireless power feeder that wirelessly feeds power from a feeding coil to a receiving coil using a magnetic field resonance phenomenon between the feeding coil and the receiving coil, the feeder comprising: a power transmission control circuit; the feeding coil; an exciting coil that is magnetically coupled to the feeding coil and feeds AC power fed from the power transmission control circuit to the feeding coil; a phase detection circuit that detects a phase difference between a voltage phase and a current phase of the AC power and generates a phase difference indicating voltage in accordance with a magnitude of the phase difference; and a reset circuit that is connected to a voltage line to which the phase difference indicating voltage is fed so as to reduce the phase difference indicating voltage, wherein the transmission power control circuit includes first and second current paths and makes first and second switches connected in series respectively to the first and second current paths alternately conductive to feed the AC power to the exciting coil, the phase difference indicating voltage output from the phase detection circuit is input to the power transmission control circuit, the power transmission control circuit adjusts the drive frequency so as to reduce the phase difference according to the phase difference indicating voltage, and the reset circuit reduces the phase difference indicating voltage when the phase difference indicating voltage exceeds a predetermined threshold.