| 摘要 |
PROBLEM TO BE SOLVED: To sense easily the separate driving of an inverter through a simple configuration by sensing the separate driving of the inverter through the cooperation of a frequency-abnormality sensing means with a phase advancing means. SOLUTION: Into the output side of a band-pass filter 203 for determining the waveshape of a reference current Isref associated with an AC output current Is, a phase advancing circuit 204 for determining the phase of the reference current Isref is inserted to drive an inverter 20 in the state of a leading power factor. Thereby, the frequency increase of an AC voltage Vs when the inverter 20 is driven separately is sensed by an over-frequency sensor 27. In this case, the over-frequency can be sensed enough by the function of a general purpose over-frequency sensor 27 and the separately driving state of the inverter 20 is sensed surely to stop it. Therefore, its separate driving can be sensed easily by a simple configuration. |
