| 摘要 |
PURPOSE:To compensate for variation in secondary resistance of the motor, by controlling the output frequency of an inverter which is controlled in proportion to the sum of a slip frequency command signal and a detected speed signal in correspondence with the variation in magnetic flux of the motor and the polarity of the slip frequency command signal. CONSTITUTION:The PWM inverter 1 is controlled in association with the operation of a comparator 13, and an induction motor 2 is driven. A magnetic flux detector 16 integrates the primary voltage of the motor 2 and detects the signal proportional to the magnitude of the magnetic flux. An amplifier 17 outputs a signal corresponding to the deviation between a command signal of the amount of the magnetic flux and the detected signal. The signal is added to an adder 6 through a polarity inverter 19. Meanwhile, a signal corresponding to the polarity of the output signal from the amplifier 5 is taken out of a comparator 18, and the polarity of the slip frequency command signal is judged. The inverter 19 inverts the polarity in correspondence with the signal from the comparator 18. A frequency proportional to a frequency command signal is generated by an oscillator 7. The output of an exciting current command circuit 8 and the output of the amplifier 5 are multiplied 10 and 9 and added 11. Thus the variation due to the temperature of the secondary resistance of the motor is corrected and controlled. |
