| 摘要 |
<p>A comply with power supply harmonic regulations becomes easy by stabilizing a current control in a power supply device that includes a power-factor improving unit. When a voltage for a load 4 is obtained by a voltage-boosting chopper circuit 3 by converting an input power supply 1 into a direct-current voltage, a switching operation is performed on a switching element 3c of the voltage-boosting chopper circuit 3, so that the input power supply 1 is short-circuited via the voltage-boosting choke coil 3a to improve a power factor. In this situation, a control unit 13 that controls the power supply device switches on and off the switching element 3c based on a comparison result between a detected input current detected by an input-current detecting unit 10 and an input-current reference signal having a sinusoidal waveform. Also, for each half cycle of the alternate-current power supply, the control unit 13 performs the switching operation on the switching element 3c a predetermined number of times counted after a zero cross is detected by a power-supply phase detecting circuit 5. After the switching operation is performed the predetermined number of times, the switching operation is prohibited so that the number of times the switching operation is performed in each half cycle of the alternate-current power supply does not vary.</p> |
