Patent ID: 9356474
Filing Date: 2016-05-31
CPC Classification: H02J

Claim Text:
1. A wireless power feeder that wirelessly feeds power from a feeding coil to a receiving coil, comprising: the feeding coil; a power transmission control circuit that supplies AC power at a drive frequency to the feeding coil to make the feeding coil feed the AC power to the receiving coil; a phase detection circuit that detects a phase difference between a voltage phase of the AC power and a current phase thereof; and a protection circuit that monitors current flowing in the feeding coil, wherein the power transmission control circuit adjusts the drive frequency in accordance with the detected phase difference, the protection circuit adjusts the detected phase difference in an increasing direction when the current flowing in the feeding coil increases, the protection circuit converts part of AC current flowing in the feeding coil into DC current, compares a first current level signal indicating a current level of the DC current and a reference level signal indicating a threshold value, and adjusts the phase difference in the increasing direction when a value of the first current level signal is greater than that of the reference level signal, and the protection circuit does not perform adjustment of the phase difference when the value of the first current level signal is smaller than that of the reference level signal.