| 摘要 |
PURPOSE:To suppress the capacity of a transformer to be small and to miniaturize a power-supply circuit which uses a resonance-type DC-DC converter. CONSTITUTION:A power-supply circuit is provided with an active filter 8 which smoothes full-wave-rectified waves obtained by a rectifying circuit 7 and which supplies a direct current to a DC-DC converter 9, with a current sensor 26 which detects the level of a current supplied to a battery 25 from the DC-DC converter 9 and with a control circuit 15 which, when the level of the detected current by the current sensor 26 is lowered, performs a control operation to raise the voltage level of the current supplied to the DC-DC converter 9 from the active filter 8. Then, the switching frequency fsw of pulse waves generated by a switching circuit 24 is set fixedly so as to correspond to the resonance frequency of an LC series resonance circuit which is composed of a resonance coil 19 and of a resonance capacitor 20. |
