The working principle of brushless motor

brushless dc motor is the use of semiconductor switching devices to achieve electronic commutation, that is, with electronic switching devices instead of the traditional contact commutator and brush. It has the advantages of high reliability, no change of spark, low mechanical noise, widely used in high-grade recording blocks, video recorders, electronic equipment and automated office equipment.
Brushless DC motor consists of permanent magnet rotor, multi-pole winding stator, position sensor and other components. The position sensor converts the current of the stator winding in a certain order according to the change of the position of the rotor (that is, the position of the rotor pole relative to the stator winding is detected and the position sensing signal is generated at the determined position and processed by the signal conversion circuit To control the power switch circuit, according to a certain logical relationship between the winding current switching). The operating voltage of the stator winding is provided by the electronic switch circuit controlled by the position sensor output.

Position sensors are magnetic, photoelectric and electromagnetic three types.
A dc brushless motor using a magnetically sensitive position sensor is mounted on a stator assembly using a magnetoresistive device (such as a Hall element, a magnetically susceptible diode, a magneto-sensitive transistor, a magnetoresistive resistor, a dedicated integrated circuit, etc.) To detect the permanent magnet, the rotor rotation when the magnetic field changes.
The use of photoelectric position sensor brushless DC motor, stator components in a certain position on the configuration of the photoelectric sensor, the rotor is equipped with a light shield, the light source for the light-emitting diode or small light bulbs. Rotor rotation, due to the role of the shading plate, the photosensitive element on the stator will be a certain frequency intermittent pulse signal. The high torque dc motor with electromagnetic position sensor is equipped with electromagnetic sensor components (such as coupling transformer, proximity switch, LC resonant circuit, etc.) on the stator assembly. When the position of the permanent magnet rotor changes, the electromagnetic effect will make the electromagnetic sensor Generates a high frequency modulated signal whose amplitude varies with the rotor position.