DC Motors

DC motors consist of one set of coils, called armature winding, inside another set of coils or a set of permanent magnets, called the stator. Applying a voltage to the coils produces a torque in the armature, resulting in motion. Stator
 The stator is the stationary outside part of a motor.
 The stator of a permanent magnet dc motor is composed of two or more permanent magnet pole pieces.
 The magnetic field can alternatively be created by an electromagnet. In this case, a DC coil (field winding) is wound around a magnetic material that forms part of the stator. Rotor
 The rotor is the inner part which rotates.
 The rotor is composed of windings (called armature windings) which are connected to the external circuit through a mechanical commutator.
 Both stator and rotor are made of ferromagnetic materials. The two are separated by air-gap. Winding A winding is made up of series or parallel connection of coils.
 Armature winding - The winding through which the voltage is applied or induced.
 Field winding - The winding through which a current is passed to produce flux (for the electromagnet)
 Windings are usually made of copper. Principle of operation of DC motor Consider a coil in a magnetic field of flux density B. When the two ends of the coil are connected across a DC voltage source, current I flows through it. A force is exerted on the coil as a result of the interaction of magnetic field and electric current. The force on the two sides of the coil is such that the coil starts to move in the direction of force.