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-phase current at the stators electromagnets. Therefore induces a current inside the rotor’s conductors, which in turns generates rotor’s magnetic field that attempts 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 construction. They are better quality and can operate in virtually 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 Induction Motor china unlike dc motors due to the absence of brushes, commutators and slip rings
Induction motors could be operated in polluted and explosive conditions as they do not have brushes which can cause sparks
AC Induction motors are Asynchronous Machines meaning that the rotor does not change at the exact same speed since the stator’s rotating magnetic field. Some difference in the rotor and stator speed is necessary to be able to develop the induction in to the rotor. The difference between the two is called the slip. Slip must be kept within an optimal range to ensure that the motor to use effectively. Roboteq AC Induction controllers can be configured to operate in one of three modes:
Scallar (or Volts per Hertz): an Open loop mode in which a command 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 Rate and Torque control that functions by optimizing the rotating field of the stator vs. this of the induced field in the rotor.
Find this video from Learning Engineering for a visual illustration on how AC Induction Motors are constructed and function.