Three phase induction motors employ a 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 work on the basic principle 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 in the rotor’s conductors, which in turns produces 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 simple and rugged in structure. They are more robust and can operate in virtually any environmental condition
Induction motors are cheaper in expense due to simple rotor construction, lack of brushes, commutators, and slip rings
They are free of maintenance motors unlike dc motors due to the lack of brushes, commutators and slip rings
Induction motors could be operated in polluted and explosive conditions as they do not have brushes that may cause sparks
AC Induction motors are Asynchronous Machines and therefore the rotor does not change at the precise same speed because the stator’s rotating magnetic field. Some difference in the rotor and stator acceleration is necessary to be able to produce the induction into the rotor. The difference between your two is named the slip. Slip should be kept within an optimal range in order for the motor to use efficiently. Roboteq AC Induction controllers could 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 change.
Controlled Slip: a Induction Motor china Closed Loop speed where voltage and frequency are controlled to keep slip inside a narrow range while working at a desired speed.
Field Oriented Control (Vector Drive): a Closed Loop Swiftness and Torque control that functions 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 work.