Three phase induction motors employ a simple construction made up of a stator covered with electromagnets, and a rotor composed of conductors shorted at each end, arranged as a “squirrel cage”. They work on the basic principle of induction in which a rotating electro-magnetic field it made through the use of a three-phase current at the stators electromagnets. Therefore induces a current within the rotor’s conductors, which in turns produces rotor’s magnetic field that attempts to check out stator’s magnetic field, pulling the rotor into rotation.

Benefits of AC Induction Motors are:

Induction motors are basic and rugged in structure. They are more robust and can operate in any environmental condition

Induction motors are cheaper in expense because of simple rotor construction, absence of brushes, commutators, and slip rings

They are free of maintenance motors unlike dc motors due to the absence of brushes, commutators and slip rings

Induction motors could be operated in polluted and Induction Motor explosive environments as they don’t have brushes which can cause sparks

AC Induction motors are Asynchronous Devices meaning that the rotor will not convert at the specific same speed as the stator’s rotating magnetic field. Some difference in the rotor and stator swiftness is necessary in order to develop the induction into the rotor. The difference between the two is called the slip. Slip must be kept in a optimal range in order for the motor to operate efficiently. Roboteq AC Induction controllers can be configured to operate in another of three modes:

Scallar (or Volts per Hertz): an Open up loop mode where a control causes a simultaneous, fixed-ratio Frequency and Voltage alter.

Controlled Slip: a Closed Loop speed where voltage and frequency are controlled to keep slip within a narrow range while running at a preferred speed.

Field Oriented Control (Vector Drive): a Closed Loop Quickness and Torque control that functions by optimizing the rotating field of the stator vs. this of the induced field in the rotor.

Find this video from Learning Engineering for a visual illustration about how AC Induction Motors are constructed and function.