Brushed DC (BDC)

Brushed DC (BDC) motors get their name from the "brushes" used for commutation. Brushed DC motors are used frequently in household appliances and in automobiles. They also maintain a strong industrial niche because of the ability to alter the torque to speed ratio exclusive to brushed motors. BDC are easy to control because speed and torque are proportional to the applied voltage / current.

A brushed DC motor is made up of 4 basic components; the stator, the rotor (or armature), brushes, and commutator. The rotor, also known as the armature made up of one or more windings. When these windings 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 windings 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 windings is called Commutation. The rotation’s direction, clockwise and/or counter clockwise, can be reversed easily by reversing the polarity of the brushes, i.e., reversing the leads on the battery.

There are four types of BDC motors. Permanent Magnet Brush DC Motor, the shunt-wound brushed DC motor, series-wound DC motor and fourth is the compound-wound brushed DC motor which is a combination of both the shunt and series wound brushed DC motors.