| 摘要 |
PURPOSE:To facilitate speed control in a high revolution region by a method wherein vector control with a speed sensor is performed if a speed is smaller than a speed at which a revolution detector can detect an accurate revolution and vector control without a speed sensor is performed if the speed is larger than that speed. CONSTITUTION:If the speed of an induction motor 1 exceeds a speed at which a revolution detector 2 can detect an accurate revolution, vector control with a speed sensor can not be performed. Therefore, a switch 12 is so turned as to have a speed signal omegar on the output side of a torque current controller 8 to perform vector control without a speed sensor. That is, the torque current controller 8 estimates the motor speed omegar so that a torque current instruction value IT' agrees with a torque current estimated value IT. With this constitution, the speed control of the induction motor can be performed even if the speed is larger than the speed at which the revolution detector can detect accurate revolution. |
