| 摘要 |
PURPOSE:To suppress the rise in the terminal voltage when a field weakening is performed by controlling the exciting component so that the magnetic flux of a motor is weakened further than the value determined inversely proportional to the speed in the speed range from the basic speed to the maximum speed. CONSTITUTION:An induction motor 3 is driven by the power converter 2 of variable voltage variable frequency, and the primary current is controlled by decomposing it into the exciting component and the torque component with the exciting current instruction signal from an exciting current instructing circuit 15 and the torque current instruction signal from a limiter 12. At this time, it is controlled to further weaken the magnetic flux of the motor by a magnetic flux instructing circuit 14 weaker than the value determined inversely proportional to the speed in the constant output range from the basis speed to the maximum speed, and the limited value of the torque current is increased by a limiter instructing circuit 13. Accordingly, the rise in the terminal voltage when the field is weakened can be suppressed, thereby controlling the field without increasing the facility capacity. |
