Three phase induction motors employ a simple construction made up of a stator covered with electromagnets, and a rotor composed of conductors shorted at each end, arranged as a “squirrel cage”. They focus on the theory of induction in which a rotating electro-magnetic field it created 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.
Great things about AC Induction Motors are:
Induction motors are simple and rugged in construction. They are more robust and can operate in any environmental condition
Induction motors are cheaper in cost due to simple rotor construction, absence of brushes, commutators, and slip rings
They are free of maintenance motors unlike dc motors due to the absence of brushes, Induction Motor commutators and slip rings
Induction motors can 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 convert at the precise same speed as the stator’s rotating magnetic field. Some difference in the rotor and stator acceleration is necessary in order to produce the induction in to the rotor. The difference between your two is called the slip. Slip must be kept within an optimal range in order for the motor to use effectively. Roboteq AC Induction controllers can be configured to operate in another of three modes:
Scallar (or Volts per Hertz): an Open up 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 controlled in order to keep slip within a narrow range while operating at a preferred speed.
Field Oriented Control (Vector Drive): a Closed Loop Quickness and Torque control that functions 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 function.