| 摘要 |
PURPOSE:To prevent the fluctuation of magnetic field during an acceleration period of a synchronous motor, by subjecting the motor to a constant excitation in a constant current acceleration region, and controlling the excitation in a speed uniforming region such that a terminal voltage of the motor is equal to a voltage of an AC power source. CONSTITUTION:In a starting period of a synchronous motor 1 operated by a frequency converter 5, an electric current is intermittently applied thereto. When the number of revolutions of the motor 1 has reached n1, the motor 1 is subjected to constant current acceleration control. A field winding 9 is controlled to a constant excitation level by a field voltage regulator 13. When the number of revolutions of the motor 1 has reached, the motor is in a speed uniforming region. A constant excitation setter 14 and a speed control unit 8 are then controlled with a signal phi from a device synchronous with the motor so as to set the terminal voltage and number of revolutions of the motor 1 in agreement with the voltage and frequency of an AC power source. After the motor 1 has been set synchronous with the AC power source, the excitation of the motor is controlled by an automatic voltage regulator 15. |
