Do You Know the Brushless Motors of Drone?

Aug. 31, 2021

As a drone propulsion testing tools supplier, I'd like to introduce it to you.

Thrust Stand and Dynamometer

Thrust Stand and Dynamometer

The Working Principle 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 reversing sparks, low mechanical noise, etc., and is widely used in high-end audio jacks, video recorders, electronic instruments and automated office equipment.

The brushless DC motor is composed of a permanent magnet rotor, a multi-pole winding stator, and a position sensor. The position sensor commutation of the stator winding current in a certain sequence according to the change of the rotor position (that is, it detects the position of the rotor pole relative to the stator winding, and generates a position sensing signal at a certain position, which is processed by the signal conversion circuit To control the power switch circuit, 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.

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

Brushless DC motors using magnetic-sensitive position sensors, whose magnetic-sensitive sensor components (such as Hall elements, magnetic diodes, magnetic sensitive pole tubes, magnetic resistors or application-specific integrated circuits, etc.) are mounted on the stator assembly. To detect the change of the magnetic field generated when the permanent magnet and the rotor rotate.

The brushless DC motor with photoelectric position sensor is equipped with a photoelectric sensor at a certain position on the stator assembly, a light shield is installed on the rotor, and the light source is a light-emitting diode or a small light bulb. When the rotor rotates, the photosensitive components on the stator will generate pulse signals intermittently at a certain frequency due to the effect of the light shield.

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 assembly. When the position of the permanent magnet rotor changes, the electromagnetic effect will cause the electromagnetic sensor Generate high frequency modulation signal (its amplitude varies with rotor position)

Brushless Motors Advantages

No Brush, Low Interference

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

Low Noise and Smooth Operation

The brushless motor has no brush, the friction is greatly reduced during operation, the operation is smooth, and the noise is much lower. This advantage is a huge support for the stability of the model.

Long Life and Low Maintenance Cost

Without the brush, the wear of the brushless motor is mainly on the bearing. From a mechanical point of view, the brushless motor is almost a maintenance-free motor. When necessary, only need to do some dust removal maintenance. Comparing the previous and the next, you know where the advantages of the brushless motor over the brushed motor are, but everything is not absolute. The performance characteristics of the brushless motor such as excellent low-speed torque performance and large torque are irreplaceable. However, In terms of the ease of use of brushless motors, with the decreasing cost of brushless controllers and the development and market competition of brushless technologies at home and abroad, brushless power systems are in the stage of rapid development and popularization, which also greatly promotes the development of the model movement.

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