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DC Brushless Motor Working Principle

Dec 25, 2019

DC Brushless Motor Working Principle


TEC3650 (2)-1


The electronic commutation of BLDCM is realized by semiconductor switch device, which is to replace the traditional contact commutator and brush with electronic switch device. It has the advantages of high reliability, no commutation spark, low mechanical noise, and is widely used in high-grade recording base, video recorder, electronic instruments and automatic office equipment.

The BLDCM consists of permanent magnet rotor, multi pole winding stator and position sensor. According to the change of the rotor position, the position sensor exchanges the current of the stator winding in a certain order (that is, detecting the position of the rotor pole relative to the stator winding, generating the position sensor signal at the determined position, controlling the power switch circuit after the signal conversion circuit processing, and switching the winding current according to a certain logical relationship). The working voltage of the stator winding is provided by the electronic switch circuit controlled by the position sensor output.

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

For the BLDCM with magnetic position sensor, the magnetic sensor (such as hall element, magnetic diode, magnetic sensitive diode, magnetic sensitive transistor, magnetic sensitive resistor or special integrated circuit) is installed on the stator assembly to detect the magnetic field change when the permanent magnet and rotor rotate.

For the BLDCM with photoelectric position sensor, the stator assembly is equipped with photoelectric sensor according to a certain position, the rotor is equipped with light shield, and the light source is led or small bulb. When the rotor rotates, the photosensitive components on the stator will generate pulse signals intermittently at a certain frequency due to the function of the light shield.

The BLDCM with electromagnetic position sensor is equipped with electromagnetic sensor components (such as coupling transformer, proximity switch, LC resonance circuit, etc.) on the stator assembly. When the permanent magnet rotor position changes, the electromagnetic effect will make the electromagnetic sensor produce high frequency modulation signal (its amplitude changes with the rotor position).


More details about DC brushless motor, please contact us via


Contact Person: Lulu Fung

E-mail: lulu@ttmotor.com

Mobile Phone: (86)158 1855 9903

Tel: (86)755-8250 1105

Add: 4th Floor, C Building, Huilongda Industrial Park, Shilong Community, Shiyan, Bao'An District, ShenZhen, China

Company Name: TT Motor (HK) Industrial Co., Ltd.

Website: www.ttmotor.com


Lulu Fung