A brushed DC motor is made up of 4 basic components; the stator, the rotor ( or armature ), brushes, and commutator.
Stator :
Generates a stationary magnetic field that surrounds the rotor, this field is generated by either:
First let us look at the stator. As the name implies, the stator generates a stationary magnetic field that surrounds the rotor and this magnetic field is generated by either permanent magnets or electromagnetic windings.
Rotor :
- Made up of one or more windings
- Commutation
Next is the rotor, also known as the armature. The rotor is made up of one or more winding's. When these winding's are energized they produce a magnetic field. The magnetic poles of this rotor field will be attracted to the opposite poles generated by the stator, causing the rotor to turn. As the motor turns, the winding's are constantly being energized in a different sequence so that the magnetic poles generated by the rotor do not overrun the poles generated in the stator. This switching of the field in the rotor winding's is called Commutation.
Brushes and Commutator :
Brushed DC motors do not require a controller to switch current in the motor windings. Instead, it uses a mechanical commutation of the windings. A copper sleeve ( commutator ), resides on the axle of the rotor. As the motor turns, carbon brushes slide over the commutator, coming in contact with different segments of the commutator. The segments are attached to different rotor windings, therefore, a dynamic magnetic field is generated inside the motor when a voltage is applied across the brushes of the motor. The brushes and commutator are the parts of a brushed DC motor that are most prone to wear.
So, as the rotor rotates inside the stator, the brushes rub the different segments of the commutator supplying a charge to that segment and its corresponding winding.
As the bushes pass over the commutator gaps the supplied electrical charge will switch commutator segments.
Thus, switching the electrical polarity of the rotor winding's. This will create an attraction of the different polarities and keep the rotor rotating within the stator field. This process will continue as long as a supply voltage is applied.
