Three phase induction motors employ a simple construction composed of a stator protected with electromagnets, and a rotor composed of conductors shorted at each end, arranged as a “squirrel cage”. They focus on the basic principle of induction where a rotating electro-magnetic field it produced by applying a three-phase 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.
Benefits of AC Induction Motors are:
Induction motors are simple and rugged in building. They are more robust and can operate in virtually any Induction Motor china environmental condition
Induction motors are cheaper in cost because of simple rotor construction, absence of brushes, commutators, and slide rings
They are free of maintenance motors unlike dc motors due to the absence of brushes, commutators and slip rings
Induction motors could be operated in polluted and explosive environments as they do not have brushes that may cause sparks
AC Induction motors are Asynchronous Devices meaning that the rotor will not change at the exact same speed because the stator’s rotating magnetic field. Some difference in the rotor and stator quickness is necessary to be able to generate the induction into the rotor. The difference between the two is called the slip. Slip must be kept in a 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 alter.
Controlled Slip: a Shut Loop speed where voltage and frequency are controlled in order to keep slip inside a narrow range while running at a preferred speed.
Field Oriented Control (Vector Drive): a Closed Loop Quickness 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 function.