Speed control of 3 phase IM

A three phase induction motor typically operates at a constant speed, making its speed control challenging. Controlling the induction motor speed can lead to reduced efficiency and a lower electrical power factor. It’s essential to understand the basic formulas for speed and torque of a three-phase induction motor, as these underpin various speed control methods. The Speed of Induction Motor is changed from Both Stator and Rotor Side. The speed control of three phase induction motor from stator side are further classified as :

V / f control or frequency control.
Changing the number of stator poles.
Controlling supply voltage.
Adding rheostat in the stator circuit.