| 摘要 |
PROBLEM TO BE SOLVED: To provide a power supply device which improves an input power factor of a power receiving circuit even in the case where a resonant frequency of a resonance circuit is not matched with a power supply frequency.SOLUTION: The power supply device comprises a power receiving coil, a bridge circuit and a smoothing capacitor. Loads are connected to both terminals of the smoothing capacitor, and the bridge circuit is formed by connecting in parallel a plurality of serial circuits of inverse parallel connection circuits of semiconductor switches and diodes. The power supply device further comprises: current detection means for detecting a current of the power receiving coil; voltage detection means for detecting a voltage between DC terminals; and a control device. Switching of the semiconductor switch is performed in such a manner that a voltage (v) between AC terminals becomes zero voltage just for an equal period α before and after a point deviating a compensation period (angle) &bgr; from one zero cross point within one cycle of an input current, the compensation period being calculated from a voltage applied to a resonance circuit formed from the power receiving coil and a resonance capacitor, and an induction voltage of the power receiving coil and that, in the other period, the voltage (v) between AC terminals becomes a positive/negative voltage defining a voltage Vbetween DC terminals as a peak value. |
