Controlling apparatus for induction motor

摘要

A controlling apparatus for an induction motor for controlling the induction motor in high efficiency having a converter for supplying an electric power to the induction motor, a rotational speed detector of the induction motor, a controlling means of the converter for holding a torque of the induction motor constant while the rotational speed of the induction motor is lower than a base rotational speed and to decrease a secondary magnetic flux of the induction motor according to the rotational speed while the rotational speed of the induction motor is over the base rotational speed, and a means for varying the secondary magnetic flux according to a terminal voltage of the induction motor so as to hold the terminal voltage a predetermined constant voltage while the rotational speed of the induction motor is higher than the predetermined speed.