Working principle of brushed motor

The brushed motor is the first type of motor that everyone comes into contact with. The motor was introduced as a model in the physics class in middle school. The main structure of the brushed motor is the stator + rotor + brush, which obtains the rotational torque through the rotating magnetic field, thereby outputting kinetic energy. The brushes are constantly in contact and friction with the commutator, and play the role of conduction and commutation during rotation.

The brushed motor adopts mechanical commutation, the magnetic pole does not move, and the coil rotates. When the motor is working, the coil and the commutator rotate, but the magnetic steel and the carbon brush do not rotate. The alternating change of the current direction of the coil is accomplished by the commutator and brush that rotate with the motor.

In a brushed motor, the process is to arrange the two power input ends of each group of coils into a ring in turn, and separate them with insulating materials to form a cylinder-like thing, which is integrated with the motor shaft. Through two small columns (carbon brushes) made of carbon elements, under the action of spring pressure, from two specific fixed positions, press the two points on the upper coil power input ring cylinder to energize a group of coils.

As the motor rotates, different coils or different two poles of the same coil are energized at different times, so that the N-S poles of the magnetic field generated by the coils and the N-S poles of the closest permanent magnet stator have a suitable angle difference. Repel each other, generate force, and push the motor to rotate. The carbon electrode slides on the coil terminal like a brush on the surface of the object, so it is called a carbon "brush".

Sliding with each other will rub the carbon brushes and cause loss, and the carbon brushes need to be replaced regularly; the on-off between the carbon brushes and the coil terminals will alternate, sparks will occur, electromagnetic breakage will occur, and electronic equipment will be disturbed.