Electric Motor Basics

Electric Motor Components and Function

• The rotor is the moving part of an electric motor that converts electrical energy into mechanical energy.
• The commutator in an electric motor's rotor is responsible for switching the current flow to the rotor windings as it rotates.

Electric Motor Operation

• When a current-carrying conductor is placed in a magnetic field, it experiences a force perpendicular to both the conductor and the magnetic field, according to the operation principle of the motor.
• This force is the primary principle behind the production of mechanical force in electric motors.
• The armature is the rotating part of an electric motor that carries the current and interacts with the magnetic field to produce torque.

Motor Types

• Permanent magnet motors rely on permanent magnets to provide the magnetic field against which the rotor field interacts to produce torque.
• The primary purpose of generators such as an alternator or a dynamo is to convert mechanical energy into electrical energy.

Motor Commutation

• Internal and external commutation is used to reverse the current in the windings in synchronism with rotation in some motor types.
• The direction of the current flow must be changed with the rotation of the motor to produce a force and torque.

Electric Motor Terminology

• Devices that convert electricity into motion but do not generate usable mechanical power as a primary objective are often referred to as actuators.
• Some motors, such as induction motors, do not have a field winding on the stator frame.

Electromagnetic Principles

• The principle discovered by Michael Faraday in 1831, which is the physical principle behind the production of mechanical force by the interactions of an electric current and a magnetic field, is electromagnetic induction.
• A device that converts electrical energy into sound waves, such as a speaker, is usually described as a transducer instead of a motor.
• Interpoles are used on large motors to improve commutation under load.