Working principle of brushless DC motor.

Working principle of brushless DC motor.

The so-called DC brushless motor has the advantages of both DC and AC motors. For the use of DC motors in the past, and even for the use of AC motors in recent years, DC brushless motors have been utilized. In terms of structure, if the stator and rotor of a permanent magnet DC servo motor with brushes are exchanged, it becomes a permanent magnet DC brushless servo motor. However, the stator coil of a brushless motor is a three-phase winding, so it is basically an AC motor, and DC brushless is the commonly used name in the industry. A brushless DC motor is a motor with excellent characteristics, which replaces the rectification part (brush and commutator) of traditional DC motors with electronic means and retains the advantages of DC motors such as rapid acceleration, proportional speed to applied voltage, and proportional torque to armature current. The characteristic of DC brushless motor ****** is the relationship of brushless construction, which theoretically does not produce noise. The excitation part of a brushless motor is composed of permanent magnets on the rotor, and the armature is located on the stator, so there is no need for electric brushes to conduct current. Therefore, its driving circuit generally uses PWM type frequency converters, combined with magnetic pole detection components such as Hall components or decomposers, to obtain smooth and stable torque, which is commonly used in situations that require high-speed and high-precision control.

The disadvantage of commonly used traditional DC motors is that the high-speed sliding between the brush and the commutator results in significant friction between the brush and commutator, causing unnecessary electrical obstacles and faults.

Improvement method: The brushless DC motor has been improved to address this drawback by replacing the faulty brushes and commutator blades with electronic components. However, the advantages of the original DC motor can still be retained, so the brushless DC motor can be said to be an improvement of the traditional DC motor.

The difference and comparison between brushless motors and brushed motors:
Brushed motors use mechanical rectifiers or electric brushes to control the commutation action. Brushless motors use electronic transistors to control the commutation action. The action of rotating output is achieved by utilizing the attraction of magnetic field force and the change of magnetic field (reversal). Electronic commutators mainly use HallSensor to sense changes in motor position to control the on or off of transistors.