| 摘要 |
PURPOSE:To hold a switching element in a turn-off state and prevent the flow of a short-circuit current to an inverter part by a method wherein, when an abnormal condition in a power supply such as a power failure, etc., generates, a controller keeps on outputting a control signal of turn-off to the switching element of the inverter part by charge-holding of a control power supply part. CONSTITUTION:A controller 33 has a PLL controlling part 20, an inverter controlling part 23, and a DC power supply controlling part 26, and also a power supply abnormality detecting part 34. An input terminal of the power supply abnormality detecting part 34 is connected to a commercial alternating current power supply and its output terminal is connected to a control terminal of the inverter controlling part 23. When the commercial alternating current power supply stops, the power supply abnormality detecting part 34 detects it to turn off a normally closed switch 35, and mechanically holds in a turn-off state until an operator resets it. Also, the power supply abnormality detecting part 34 outputs a continuous command signal from the output terminal to supply it to the control terminal of the inverter control part 23, which controls so as to keep on outputting a gate signal supplied to the control terminal of an inverter part 14. |
