| 摘要 |
PROBLEM TO BE SOLVED: To increase the torque of an induction motor in a low-speed range, and suppress the vibration of the torque of the motor which occurs when a load torque is abruptly applied to the motor. SOLUTION: In a method for controlling the speed of an induction motor, a q-axis current command value Iq is made to substantially zero when the absolute value of a speed command value ωr * or speed estimate value ωr ^ is smaller than a set value and, when the difference between the speed command value ωr * and the speed estimate value ωr ^ shows an increasing trend, a value obtained by increasing the speed command value ωr * based on the difference is used as a frequency command value ω1 ***. When the difference shows a decreasing trend, a value which is obtained by decreasing the speed command value ωr * based on the difference is used as the frequency command value ω1 ***. |
