Three phase induction motors have a very 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 work on the basic principle of induction where a rotating electro-Induction Motor magnetic field it developed through the use of a three-phase current at the stators electromagnets. This in turn induces a current within the rotor’s conductors, which in turns produces rotor’s magnetic field that tries to follow 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 any environmental condition
Induction motors are cheaper in expense due to simple rotor construction, absence of brushes, commutators, and slip rings
They are maintenance free motors unlike dc motors due to the absence of brushes, commutators and slip rings
Induction motors can be operated in polluted and explosive conditions as they don’t have brushes which can cause sparks
AC Induction motors are Asynchronous Machines meaning that the rotor will not turn at the specific same speed because 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 named the slip. Slip must be kept within an optimal range in order for the motor to operate efficiently. Roboteq AC Induction controllers could be configured to operate in one of three modes:
Scallar (or Volts per Hertz): an Open loop mode where a command causes a simultaneous, fixed-ratio Frequency and Voltage alter.
Controlled Slip: a Closed Loop speed where voltage and frequency are controlled in order to keep slip inside a narrow range while operating at a desired speed.
Field Oriented Control (Vector Drive): a Closed Loop Acceleration 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.