Three phase induction motors employ a simple construction made up of a stator protected with electromagnets, and a rotor composed of conductors shorted at each end, arranged as a “squirrel cage”. They work on the theory of induction in which a rotating electro-magnetic field it developed by applying a three-stage current at the stators electromagnets. Therefore induces a current within 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.
Benefits of AC Induction Motors are:
Induction motors are basic and rugged in structure. 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 unlike dc motors because of the absence of brushes, commutators and slip rings
Induction motors can be operated in polluted and explosive conditions as they do not have brushes which can cause sparks
AC Induction motors are Asynchronous Devices meaning that the rotor will not change at the precise same speed since the stator’s rotating magnetic field. Some difference in the rotor and stator swiftness is necessary to be able to generate the induction in to the rotor. The difference between your two is called the slip. Slip should be kept within an optimal range in order for the motor to operate efficiently. Roboteq AC Induction controllers can be configured to operate in another of three modes:
Scallar (or Volts per Hertz): an Open loop mode where a control causes a simultaneous, fixed-ratio Frequency and Voltage modify.
Controlled Slip: a Closed Loop speed where voltage and frequency are controlled in order to keep slip inside a narrow range while running at a desired speed.
Field Oriented Control (Vector Drive): a Closed Loop Rate and Torque control that works by Induction Motor 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 about how AC Induction Motors are constructed and function.