Analysis of armature reaction of brushless motor

Brushless motor consists of a motor body and a driver, and is a typical electromechanical integrated product. Due to the self controlled operation of brushless DC motors, they do not require additional starting windings on the rotor like synchronous motors that start under heavy loads under variable frequency speed regulation, nor do they produce oscillations and loss of step during sudden load changes. The armature reaction and commutation are important points in the basic theory of brushless motors. The armature is an important component of brushless motors during operation.

1. Armature reaction: When a brushless motor operates under load, both the main magnetic pole and the armature magnetic field exist simultaneously, and the influence of the armature magnetic field on the main magnetic field is called armature reaction. The result of armature reaction is distortion of the synthesized magnetic field, asymmetry of the synthesized magnetic field, which makes it difficult to reverse direction and increases the spark during commutation.
2. Commutation: During the operation of a brushless motor, when the armature winding components pass through the electric brush, the direction of current changes from one branch to another, and this process is called commutation.
3. Due to the high motor speed and fast commutation, self induced electromotive force will be generated, forming sparks.
The armature reaction and commutation of brushless motors can generate sparks. In order to reduce sparks, it is usually necessary to install commutation poles and increase brush resistance (the brushes are made of graphite, which is wear-resistant and has high resistance).
2024.7.31  ZG