Three phase induction motors have a very Induction Motor simple construction made up of a stator covered with electromagnets, and a rotor made up of conductors shorted at each end, arranged as a “squirrel cage”. They focus on the theory of induction where a rotating electro-magnetic field it made through the use of a three-stage current at the stators electromagnets. Therefore induces a current inside the rotor’s conductors, which in turns produces rotor’s magnetic field that tries 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 structure. They are better quality and can operate in any environmental condition
Induction motors are cheaper in cost because of simple rotor construction, absence of brushes, commutators, and slip 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 conditions as they do not have brushes which can cause sparks
AC Induction motors are Asynchronous Machines meaning that the rotor will not switch at the exact same speed because the stator’s rotating magnetic field. Some difference in the rotor and stator swiftness is necessary in order to develop the induction in to the rotor. The difference between your two is called the slip. Slip must be kept in a optimal range in order for the motor to operate effectively. Roboteq AC Induction controllers can be configured to operate in another of three modes:
Scallar (or Volts per Hertz): an Open loop mode in which 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 inside a narrow range while running 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.
See this video from Learning Engineering for a visual illustration on how AC Induction Motors are constructed and function.