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 where a rotating electro-magnetic field it developed through the use of a three-stage current at the stators electromagnets. Therefore induces a current inside the rotor’s conductors, which in turns produces 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 building. They are more robust and can operate in any environmental condition
Induction motors are Induction Motor cheaper in expense because of simple rotor construction, absence of brushes, commutators, and slide rings
They are free of maintenance motors unlike dc motors due to the lack of brushes, commutators and slip rings
Induction motors can be operated in polluted and explosive conditions as they do not have brushes that may cause sparks
AC Induction motors are Asynchronous Machines meaning that the rotor does not switch at the exact same speed since the stator’s rotating magnetic field. Some difference in the rotor and stator rate is necessary to be able to make the induction in to the rotor. The difference between your two is called the slip. Slip must be kept in a 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 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 managed in order to keep slip within a narrow range while operating at a desired speed.
Field Oriented Control (Vector Drive): a Closed Loop Rate and Torque control that works by optimizing the rotating field of the stator vs. this of the induced field in the rotor.
Observe this video from Learning Engineering for a visual illustration on how AC Induction Motors are constructed and function.