Three phase induction motors have a very simple construction composed of a stator covered with electromagnets, and a rotor made up of conductors shorted at each end, arranged as a “squirrel cage”. They focus on the theory of induction where a rotating electro-magnetic field it produced through the use of a three-stage current at the stators electromagnets. Therefore induces a current in the rotor’s conductors, which in turns generates rotor’s magnetic field that attempts to follow 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 Induction in Motor operate in any environmental condition

Induction motors are cheaper in expense due to simple rotor construction, absence of brushes, commutators, and slide rings

They are free of maintenance motors unlike dc motors because of the lack of brushes, commutators and slip rings

Induction motors can be operated in polluted and explosive environments as they don’t have brushes that may cause sparks

AC Induction motors are Asynchronous Devices and therefore the rotor does not switch at the exact same speed because the stator’s rotating magnetic field. Some difference in the rotor and stator swiftness is necessary to be able to generate the induction into the rotor. The difference between the two is called the slip. Slip must be kept within an optimal range in order for the motor to use efficiently. Roboteq AC Induction controllers could be configured to operate in another of three modes:

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

Controlled Slip: a Closed Loop speed where voltage and frequency are managed to keep slip inside a narrow range while operating at a desired speed.

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

See this video from Learning Engineering for a visual illustration on how AC Induction Motors are constructed and work.