| 摘要 |
PURPOSE:To suppress a rise in a DC voltage by detecting a state of DC overvoltage of a PWM rectifier due to a current from a bypass circuit, by making the PWM rectifier conduct an inverter operation by switching it from an ordinary charging mode over to a regenerative mode on the basis of a signal of this detection and by returning thereby an effective power stored in a DC circuit onto the AC input side. CONSTITUTION:When a DC overvoltage is detected in a state wherein an inverter output and a bypass output lap over, an analog switch 25 is turned ON through an AND gate 223, an NAND gate 225, a flip-flop 226 and an NOT circuit 227 and a voltage adjustment signal is made low forcedly through an addition circuit 23 and an inversion circuit 24 so that a PWM rectifier 4 be set in a regenerative mode. Thereby an input current set value of the PWM rectifier is decreased and the PWM rectifier is made to conduct a regenerative operation, so that an effective power stored in a DC current thereof be returned onto the AC input side (commercial power source side). Accordingly, the state of the DC overvoltage of the PWM rectifier is suppressed. |
