Answer to Question #231589 in Electrical Engineering for Mohammad Hossain

Question

Assignment by speed control of three phase induction motor

Answer 1

Because a three-phase induction motor is essentially a constant speed motor, controlling its speed is fairly challenging. Induction motor speed control comes at the expense of decreased efficiency and a low electrical power factor. Before addressing the techniques for controlling the speed of a three-phase induction motor, it is necessary to understand the fundamental formulae for speed and torque of a three-phase induction motor, as the speed control methods are dependent on these formulas.

The speed of an induction motor may be adjusted from both the stator and the rotor. The speed regulation of a three-phase induction motor from the stator side is further subdivided as follows:

Controlling voltage and frequency.

Increasing or decreasing the number of stator poles.

Managing the supply voltage.

Incorporating a rheostat into the stator circuit.

The rotor-side speed controls of a three-phase induction motor are further categorized as follows:

Increasing external resistance on the rotor side.

Cascade control is a type of control technique.

Slip frequency emf is being injected into the rotor side.