Brushless DC motor uses semiconductor switching devices to realize electronic commutation, that is, replacing traditional contact commutators and brushes with electronic switching devices. Brushless DC motor products have the advantages of high reliability, no reversing sparks, and low mechanical noise. They are widely used in high-end audio jacks, video recorders, electronic instruments and automated office equipment.

Brushless DC motor consists of permanent magnet rotor, multi-pole winding stator, position sensor, etc. The position sensor commutation of the stator winding current in a certain sequence according to the change of the rotor position (that is, it detects the position of the rotor pole relative to the stator winding, and generates a position sensing signal at a certain position, which is processed by the signal conversion circuit To control the power switch circuit, switch the winding current according to a certain logical relationship). The manufacturer of Brushless DC motor tells you that 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.
Brushless DC motor adopts magnetic position sensor. Its magnetic sensor components (such as Hall element, magneto-sensitive diode, magneto-sensitive pole tube, magneto-sensitive resistor or application specific integrated circuit, etc.) are installed on the stator assembly. Detect changes in the magnetic field generated when the permanent magnets and rotors rotate.
The Brushless DC motor with photoelectric position sensor is equipped with a photoelectric sensor at a certain position on the stator assembly, a light shield is installed on the rotor, and the light source is a light-emitting diode or a small bulb. When the rotor rotates, the photosensitive components on the stator will generate pulse signals intermittently at a certain frequency due to the effect of the light shield.
Brushless DC motor products using electromagnetic position sensors are equipped with electromagnetic sensor components (such as coupling transformers, proximity switches, LC resonant circuits, etc.) on the stator assembly. When the position of the permanent magnet rotor changes, the electromagnetic effect will cause the electromagnetic sensor Produces a high-frequency modulation signal (the amplitude of which varies with the position of the rotor).