Three phase induction motors employ a simple construction composed of a stator covered with electromagnets, and a rotor composed of conductors shorted at each end, arranged as a “squirrel cage”. They focus on the basic principle of induction where a rotating electro-magnetic field it made by applying a three-stage current at the stators electromagnets. This in turn induces a current in the rotor’s conductors, which in turns generates 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 building. They are Induction in Motor better quality and can operate in any environmental condition
Induction motors are cheaper in cost due to simple rotor construction, lack of brushes, commutators, and slip 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 environments as they don’t have brushes that may cause sparks
AC Induction motors are Asynchronous Devices meaning that the rotor does not turn at the exact same speed as the stator’s rotating magnetic field. Some difference in the rotor and stator quickness 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 in order for 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 command causes a simultaneous, fixed-ratio Frequency and Voltage modify.
Controlled Slip: a Closed Loop speed where voltage and frequency are controlled in order to keep slip within a narrow range while running at a desired 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.
Observe this video from Learning Engineering for a visual illustration about how AC Induction Motors are constructed and function.