| 摘要 |
PURPOSE:To make possible the high speed rotation of a motor even when its number of rotations is exceeded and prevent unnecessary exciting current components from being passed in case motor current is increased, by creating a relative phase angle of the rotor relative to motor current so that the magnetic flux within the motor will be made proper. CONSTITUTION:A relative phase angle creating means 9 creates a relative phase angle A to reduce exciting current components in proportion to I/SD with the increase in number of rotations SD. The relative phase angle creating means thereby reduces the exciting current component of a motor to a specified value or below when its base number of rotations is not reached, and keeps the counter electromotive force of the motor almost constant when the base number of rotations is exceeded. A current amplitude commanding means 8 is fed with torque command T and outputs current amplitude command IOS. As a result, the relative phase angle of the rotor relative to motor current is reduced and thus high speed rotation is feasible when the base number of rotations of the motor is exceeded. In addition, relative phase angle is reduced and thus the passage of an unnecessary exciting current component is prevented when motor current is in proximity to or above the rated value. |
