Patent ID: 8841887

Claim:
A power supply device including a rectification means for synchronously rectifying three-phase AC voltages generated by a generator so as to produce a charging voltage for charging up a battery; a switch control means for controlling each of semiconductor switches, constituting the rectification means, at intervals in response to a charging status of the battery; a negative voltage detection means for detecting a negative voltage at each of three phases of the three-phase AC voltages; and a voltage detection means for detecting the battery voltage being higher than a predetermined voltage, wherein when the negative voltage or the battery voltage higher than the predetermined voltage is detected, the switch control means controls each of the semiconductor switches, the power supply device comprising: an abnormality detection means for monitoring a status of the negative voltage at each phase detected by the negative voltage detection means and thereby detecting an abnormality in at least one of the three phases; wherein when the abnormality detection means detects an abnormality in the negative voltage of a phase, the abnormality detection means through the switch control means controls only a semiconductor switch, among the semiconductor switches, which corresponds to the phase of the abnormality.