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

Great things about AC Induction Motors are:

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

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

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

Induction motors can be operated in polluted and explosive environments as they do not have brushes which can cause sparks

AC Induction motors are Asynchronous Machines and therefore the rotor does not convert at the specific same speed because the stator’s rotating magnetic field. Some difference in the rotor and stator velocity is necessary to be able to generate the induction into the rotor. The difference between your two is named the slip. Slip must be kept within an optimal range in order for the motor to operate effectively. Roboteq AC Induction controllers could be configured to operate in one of three modes:

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

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

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

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