An induction engine or asynchronous motor is an AC electric engine 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.
Great things about AC Induction Motors are:
Induction motors are simple and rugged in structure. They are better quality and can operate in virtually any environmental condition
Induction motors are cheaper in cost because of simple rotor construction, lack of brushes, commutators, and slide rings
They are maintenance free motors unlike dc motors because of the lack of brushes, commutators and slip rings
Induction motors could be operated in polluted and explosive environments as they don’t have brushes which can cause sparks
AC Induction motors are Asynchronous Machines and therefore the rotor does not switch at the precise same speed because the stator’s rotating magnetic field. Some difference in the rotor and stator speed is necessary to be able to make the induction in to the rotor. The difference between the two is named the slip. Slip must be kept in a optimal range in order for the motor to operate efficiently. Roboteq AC Induction controllers could 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 Shut Loop speed where voltage and frequency are managed in order to keep slip within a narrow range while working at a ac motor desired speed.
Field Oriented Control (Vector Drive): a Closed Loop Acceleration 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 work.
