| 摘要 |
PROBLEM TO BE SOLVED: To improve the acceleration characteristic in an excessive state of an induction motor, by shifting a voltage-limiting ellipse by a specified value and an increment with respect to the axis showing the current value of torque portion, and by increasing torque in the excessive state in comparison with a normal state. SOLUTION: In a method for controlling weak field for an induction motor, when current and voltage limits in an excessive state are shown on a current plane, it is shown in a state that, in the excessive state during the operation of the induction motor, that the voltage limiting range expressed with an ellipse with respect to the current limit expressed with a circle on the current plane is shifted by δ with respect to the torque portion current axis in a synchronized coordinate system. Here, when the equation of a stator voltage in the synchronized coordinate system based on the excessive characteristics of the magnetic flux of a rotor is solved in combination with the described limiting conditions, the voltage-limiting ellipse shifted by approximately δ is formed. By obtaining the points of intersection of the voltage-limiting ellipse with the current-limiting circle, the current values of the magnetic flux portion and the torque portion of the rotor which show maximum torque in the weak field range are obtainable. |
