Three phase induction motors employ a simple construction made up of a stator protected with electromagnets, and a rotor made up 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 created by applying a three-stage current at the stators electromagnets. This in turn induces a current in the rotor’s conductors, which in turns produces rotor’s magnetic field that Induction in Motor attempts 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 building. They are better quality and can operate in virtually 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 due to the lack of brushes, commutators and slip rings
Induction motors could 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 will not change at the specific same speed as the stator’s rotating magnetic field. Some difference in the rotor and stator rate is necessary to be able to produce the induction in to the rotor. The difference between your two is named the slip. Slip should be kept in a optimal range to ensure that 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 order causes a simultaneous, fixed-ratio Frequency and Voltage alter.
Controlled Slip: a Shut Loop speed where voltage and frequency are controlled to keep slip within a narrow range while running at a preferred speed.
Field Oriented Control (Vector Drive): a Closed Loop Swiftness and Torque control that works by 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 work.