Three phase induction motors employ a simple construction made up 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 principle of induction in which a rotating electro-magnetic field it made by applying a three-stage Induction Motor current at the stators electromagnets. Therefore induces a current inside the rotor’s conductors, which in turns creates 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 simple and rugged in building. They are more robust and can operate in any environmental condition
Induction motors are cheaper in expense because of simple rotor construction, absence 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 conditions as they do not have brushes that may cause sparks
AC Induction motors are Asynchronous Devices and therefore the rotor does not convert at the precise same speed because the stator’s rotating magnetic field. Some difference 
in the rotor and stator acceleration is necessary to be able to generate the induction in to the rotor. The difference between the two is called the slip. Slip should be kept in a optimal range in order for the motor to use efficiently. 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 modify.
Controlled Slip: a Closed Loop speed where voltage and frequency are managed to keep slip within a narrow range while working at a preferred speed.
Field Oriented Control (Vector Drive): a Closed Loop Speed 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 about how AC Induction Motors are constructed and function.