Basic working principle of brushless motor.

Basic working principle of brushless motor.

Brushless DC motors use semiconductor switching devices to achieve electronic commutation, replacing traditional contact commutators and brushes with electronic switching devices. It has the advantages of high reliability, no commutation sparks, and low mechanical noise, and is widely used in high-end recording stands, video recorders, electronic instruments, and automated office equipment.

A brushless DC motor consists of a permanent magnet rotor, a multi pole winding stator, a position sensor, and other components. Position sensing converts the current of the stator winding in a certain order according to the change in rotor position (i.e. detects the position of the rotor magnetic pole relative to the stator winding and generates a position sensing signal at a determined position, which is processed by a signal conversion circuit to control the power switch circuit and switch the winding current according to a certain logical relationship). The working voltage of the stator winding is provided by an electronic switch circuit controlled by the output of the position sensor.

There are three types of position sensors: magnetic sensitive, photoelectric, and electromagnetic.

A brushless DC motor using a magnetic sensitive position sensor, whose magnetic sensing devices (such as Hall elements, magnetic sensitive diodes, magnetic sensitive polarizing tubes, magnetic sensitive resistors, or dedicated integrated circuits) are mounted on the stator assembly to detect changes in the magnetic field generated by the rotation of the permanent magnet and rotor.