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.
The speed controls of three phase induction motor from rotor side
are further classified as:
Adding external resistance on rotor side.
Cascade control method.
Injecting slip frequency emf into rotor side.