An induction engine or asynchronous 
motor is an AC electric motor in which the electric energy in the rotor had a need to create torque is obtained by electromagnetic induction from the magnetic field of the stator winding. … An induction motor’s rotor can be either wound type or squirrel-cage type.
Benefits of AC Induction Motors are:
Induction motors are simple and rugged in construction. They are more robust and can operate in virtually 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 absence of brushes, commutators and slip rings
Induction motors can be operated in polluted and explosive environments as they do not have brushes which can cause sparks
AC Induction motors are Asynchronous Devices meaning that the rotor does not turn at the precise same speed as the stator’s rotating magnetic field. Some difference in the rotor and stator speed is necessary in order to generate the induction into the rotor. The difference between the two is named the slip. Slip should be kept within an optimal range to ensure that 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 change.
Controlled Slip: a Closed Loop speed where voltage and frequency are controlled in order to keep slip within a narrow range while working at a desired speed.
Field Oriented Control (Vector Drive): a Closed Loop Acceleration and Torque control that ac motor functions 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 function.