摘要 |
Power is fed from a power feeding coil L2 to a power receiving coil L3 by magnetic resonance. A VCO 202 alternately turns ON/OFF switching transistors Q1 and Q2 at a drive frequency fo, whereby AC power is supplied to the power feeding coil L2, and then the AC power is supplied from the power feeding coil L2 to the power receiving coil L3. A phase detection circuit 114 detects a phase difference between current and voltage phases, and the VCO 202 adjusts the drive frequency fo such that the phase difference becomes zero. When load voltage is changed, the detected voltage phase value is adjusted with the result that the drive frequency fo is adjusted. |