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

Benefits of AC Induction Motors are:

Induction motors are simple and rugged in construction. They are better quality and can operate in any environmental condition

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

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

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

AC Induction motors are Asynchronous Machines and therefore the rotor will not convert at the exact same speed because the stator’s rotating magnetic field. Some difference in the rotor and stator speed is necessary in order to create the induction into the rotor. The difference between your two is named the slip. Slip must be kept within an optimal range to ensure that the motor to use efficiently. Roboteq AC Induction controllers can be configured to operate in another of three modes:

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

Controlled Slip: a Shut Loop speed where voltage and frequency are managed in order to keep slip within a narrow range while operating at a desired speed.

Field Oriented Control (Vector Drive): a Closed Loop Quickness and Torque control that works 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 work.