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July 13, 2020

Three phase induction Induction in Motor motors have a very simple construction made up of a stator protected 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 in which a rotating electro-magnetic field it made by applying a three-phase current at the stators electromagnets. This in turn induces a current inside the rotor’s conductors, which in turns generates rotor’s magnetic field that tries to follow stator’s magnetic field, pulling the rotor into rotation.

Benefits of AC Induction Motors are:

Induction motors are basic 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 slide rings

They are maintenance free motors unlike dc motors because of the lack of brushes, commutators and slip rings

Induction motors can be operated in polluted and explosive environments as they don’t have brushes which can cause sparks

AC Induction motors are Asynchronous Machines meaning that the rotor will not change at the precise same speed as the stator’s rotating magnetic field. Some difference in the rotor and stator speed is necessary to be able to make 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 can be configured to operate in one of three modes:

Scallar (or Volts per Hertz): an Open up loop mode where a order causes a simultaneous, fixed-ratio Frequency and Voltage modify.

Controlled Slip: a Shut Loop speed where voltage and frequency are managed to keep slip within a narrow range while operating at a desired 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.

See this video from Learning Engineering for a visual illustration about how AC Induction Motors are constructed and work.