| 摘要 |
PURPOSE: To obtain a control device which can prevent an over-current from being generated in the restoration of a service interruption by a method wherein, after the service interruption of an arithmetic part, a frequency command value which makes an induction motor repeat a synchronous operation and a regenerative operation is output and a frequency command value which is raised after it has been lowered along the number of free-running revolutions of the induction motor is output after the restoration of the service interruption. CONSTITUTION: A detected output signal which has detected the service interruption and the restoration of the service interruption of an AC power supply 1 by means of a detection part 10 and a detected output signal which has detected the number of revolutions of an induction motor 5 by means of a detection part 12 are input to a frequency-command-value arithmetic part 13, and a frequency command value is output to a voltage and frequency control part 7 so as to control an inverter 4. At this time, after the service interruption of the frequency-command-value arithmetic part 13, a frequency command value which makes the induction motor 5 repeat a synchronous operation and a regenerative operation is output. After the restoration of the service interruption, a frequency command value which is raised after it has been lowered along the number of free-running revolutions of the induction motor 5 is output. Thereby, it is possible to prevent an overcurrent from being generated in the restoration of the service interruption, and it is possible to prevent the generation of an overcurrent trip and the destruction of a switching element. |
