The working principle and advantages of brushless DC motor


1. Working principle of brushless DC motor: The paramet […]

1. Working principle of brushless DC motor:

The parameter index of this type of brushless DC motor, in addition to dimensions (outer diameter, length, shaft diameter, etc.), weight, voltage range, no-load current, maximum current and other parameters, there is an important index-KV value, no. The unique performance parameters of brush motors are important data for judging the performance characteristics of brushless motors.


Brushless DC motors use semiconductor switching devices to achieve electronic commutation, that is, electronic switching devices are used to replace traditional contact commutators and brushes. It has the advantages of high reliability, no reverse sparks and low mechanical noise. It is widely used in high-end audio jacks, video recorders, electronic instruments and automated office equipment.


The brushless DC motor consists of a permanent magnet rotor, a multi-pole winding stator, and a position sensor. According to the change of the rotor position, the stator winding current is commutated by the position sensor in a certain order (that is, the position of the rotor magnetic pole relative to the stator winding is detected, and the position induction signal is generated at a certain position, which is processed by the signal conversion circuit. The power switch circuit should be controlled. , Please switch the winding current according to a certain logical relationship). The working voltage of the stator winding is provided by an electronic switch circuit controlled by the output of the position sensor.


Position sensors are divided into three types: magnetic sensitive, photoelectric and electromagnetic.


For brushless DC motors that use magnetic position sensors, magnetic sensor components (such as Hall elements, magnetic diodes, magnetopole tubes, magnetic resistors or application-specific integrated circuits, etc.) are installed on the stator assembly. Detect changes in the magnetic field generated when the permanent magnet and the rotor rotate.


The brushless DC motor uses a photoelectric position sensor. The photoelectric sensor is arranged at a certain position on the stator assembly, the rotor is equipped with a light shield, and the light source is a light emitting diode or a small bulb. When the rotor rotates, due to the role of the light shield, the photosensitive element on the stator will intermittently generate pulse signals at a certain frequency. Brushless DC motors using electromagnetic position sensors are equipped with electromagnetic sensor components (such as coupling transformers, proximity switches, LC resonance circuits, etc.) on the stator components. When the position of the permanent magnet rotor changes, the electromagnetic effect will cause the electromagnetic sensor to produce a high-frequency modulation signal (the amplitude of which varies with the position of the rotor).



2. Advantages of brushless DC motor:


1) Brushless, low interference

The brushless motor removes the brush. The most direct change is that no electric spark is generated when the brush motor is running, which greatly reduces the interference of the electric spark on the remote control radio equipment.


2) Low noise, stable operation

The brushless motor has no brush, the friction is greatly reduced during operation, the operation is stable, and the noise is low. This advantage provides great support for the stability of the model.


3) Long life and low maintenance cost

Without brushes, the wear of brushless motors is mainly on the bearings. From a mechanical point of view, brushless motors are almost maintenance-free motors. When necessary, only some dust removal maintenance is required. Comparing the top and bottom, we know the advantages of brushless motors over brush motors, but they are not absolute. Brushless DC motors cannot replace the performance characteristics of brush motors, such as excellent low-speed torque performance and large torque. However, from the perspective of the convenience of brushless motors, with the declining cost of brushless controllers, the development of brushless technologies at home and abroad, and the increasingly fierce market competition, brushless power systems are rapidly developing and popularizing. The earth has promoted the development of brushless motors. Promoted the development of model sports.

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