| 摘要 |
PURPOSE:To prevent the damage of a load by deenergizing a switching rectifier becoming defective and energizing a normal switching element connected in parallel with the load when an AC/DC converter becomes defective. CONSTITUTION:When an AC/DC converter C1 becomes defective so that an overcurrent flows to a circuit, the fact that a defect occurs in the converter C1 is detected by a current zero detector 42, and a defective current detection signal is supplied to a start/stop controller 40. As a result, a gate block signal which opens the gates of the thyristors V1-V6 of the converter C1 is outputted from the controller 40, bypass pair signals for turning a pair of thyristors of the thyristors V7-V12 ON and for turning the gates of the remaining pairs of the thyristors OFF are outputted. When a current flowing through the converter C1 becomes zero, a detection signal is supplied from a current zero detector 42 to the controller 40, and the current flowing through an AC/DC converter C2 becomes zero. |
