METHOD AND APPARATUS FOR CONTROLLING AND DRIVING INDUCTION MOTOR.

摘要

A method and apparatus for controlling and driving an induction motor, by which its constant output power can be generated in a wide rotating range. Each of the star-connected windings of the induction motor is divided into two parts, (5t and 3t), at a predetermined ratio of their numbers of turns (e.g. 5:3). At a low speed, only changeover switches MC2 are closed, and through the divided windings (5t and 3t), currents flow. At a medium speed, only changeover switches MC3 are closed, and only through the divided windings (5t), currents flow. At a high speed, only changeover switches MC1 are closed, and only through the divided windings (3t), currents flow. That is, the induction motor is driven, by changing over the number of turns of each winding into one of three stages, so as to make it large at a low speed and make it small as the speed of the motor is increased.