User Manual

Table Of Contents
Introduction to AC Induction Motors
Advanced Digital Motor Controller User Manual 127
SECTION 9
AC Induction
MotorOperation
This section discusses the controller’s operating features and options when using three
phase AC Induction motors.
Introduction to AC Induction Motors
Three phase induction motors are the most common types of electrical motors. They have
a very simple construction composed 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 principle of induction where a rotating electro-magnetic field it created by applying a
three-phase current at the stators electromagnets. This in turn induces a current inside the
rotor’s conductors, which in turns produces rotors magnetic field that tries to follow sta-
tor’s magnetic field, pulling the rotor into rotation.
Stator
Rotor
Benefits of 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 brush-
es, commutators, and slip rings