| 摘要 |
PURPOSE:To operate an induction motor stably even in low frequency region by providing a voltage command, separated vectorially into a flux component and a torque component, and correcting the voltage command according to the variation rate of load per motor based on the ratio of torque current to flux current. CONSTITUTION:A voltage command value compensating circuit 10 comprises a coefficient unit 101 in which a constant corresponding to the leakage inductance per a single motor is set, a coefficient unit 102 for converting a frequency into an angular frequency, and multipliers 103, 104, 105. The multiplier 105 multiplies a current ratio iq/id outputted from a divider 13 by an output Vdo* from a flux component voltage setter 91 and the product is then added to a torque component voltage command value Vqo* in an adder 12 thus obtaining a voltage command Vqn*. On the hand, it is multiplied by the leakage inductance Lo and further multiplied by an angular frequency omega* in the multiplier 104. Output from the multiplier 104 is then multiplied by a flux component current command value ido* in the multiplier 103 and the flux component voltage command value Vdo* is subtracted from the product in a subtractor 11 thus obtaining a voltage command Vdn*. |
