NOISELESS VARIABLE-SPEED SQUIRREL-CAGE INDUCTION-MOTOR

A new variable speed squirrel-cage induction motor is proposed in this paper, made up of a squirrel-cage rotor and two stators, where one of them can be turned for speed control. The proposed motor has the following special features: (1) The range of speed control is extremely wide and the motoring operation is almost constant-torque under the constant supply source voltage and frequency. (2) No special source like an inverter is required; no harmonics and low-vibration can be realized. (3) Smooth operation from the starting to the rated speed can be expected without any special starter because of suppressed starting current and large starting torque. In this paper, the analysis method of its characteristics are described. This is followed by the results of the analysis and experiments on a test motor, and the characteristics of the motor are discussed. © 1990 IEEE