Commutators

An essential part of DC brushed and brushless motors, a commutator is a device which converts the supplied DC into AC for the operation of the motor (so, in truth, DC motors do eventually run on AC power after all). In brushed motors, the commutator is internally operated with the rotor and brushes, which will reverse the current according to every 180 degrees of the rotor. This means that the magnetic field given by the current is always turning the motor around in the same direction. Without a commutator, the motor would just turn 180 degreen in one direction, then turn back 180 degrees in the other, and just so on and so forth.

The basic principle of a commutator is that an electric current is supplied through the motor: into one magnet, and out of the other. When the rotor has turned 180 degrees however, the brushes meet a break in between the two semi-cylindrical magnets. However the kinetic energy of the rotor from the previous cycle keeps it moving, and the magnets continue rotating, and come into contact with the same brushes, but the other way roundm keeping the rotor moving.