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Discussion on Performance of Negative Pressure Fan DC Brushless Motor

2020-01-19 10:25:32 Volcano Motor Read

Fan EC Motor Permanent Magnet Synchronous Motor Selection Key Part Sixteen ---Discussion on Performance of Domestic Negative Pressure Fan DC Brushless Motor

Negative Pressure Fan DC Brushless Motor.jpg

Negative pressure fan (industrial ventilation market) is probably the first market in China's fan industry to understand EC motor or fan permanent magnet synchronous motor and apply it on a large scale. Negative pressure fan (industrial ventilation market) started to know about permanent magnet synchronous motor of fan in 2016, and gradually promoted the application of DC brushless motor of fan in 2018. The industry consumption reached a certain amount in 2019. Only from the purchase figures of DC brushless motor of fan, the market stage of negative pressure fan (industrial ventilation market) is much higher than that of negative pressure fan (animal husbandry fan market) in other fields.


Why not refer to the permanent magnet motor of negative pressure fan (industrial ventilation market) as EC motor or fan permanent magnet synchronous motor, but as fan DC brushless motor? We should start with the market structure.


Negative pressure fan (industrial ventilation market) from matching asynchronous motor to matching fan DC brushless motor, the fundamental demand is not to improve product performance, but to find selling points. At present, there are many fan DC brushless motors in the market that were developed by the original industrial ventilation engineering manufacturer "uprising". Affected by the development stage of negative pressure fan (industrial ventilation market), the practitioners in this industry have no professional knowledge of fluid mechanics, permanent magnet synchronous motor and DC brushless motor. Therefore, negative pressure fans (industrial ventilation market) cannot meet the more fundamental and long-term needs of high-performance fans.


As I said before, the essence of fan EC motor and fan permanent magnet synchronous motor is "a high performance fan power system with permanent magnet synchronous motor +FOC vector controller designed and optimized necessary for the structure, performance and function of telephone controller according to the application characteristics". So what is the performance of domestic negative pressure fan DC brushless motor?


At present, there are several products for domestic negative pressure fans (industrial ventilation market) DC brushless motors (0.75KW/460 rpm):

Product A: surface-mounted internal rotor DC brushless motor+square wave controller; No communication control, Hall control; The motor/controller is installed separately.

surface-mounted internal rotor DC brushless motor.png

Product B: surface-mounted inner rotor DC brushless motor+square wave controller; Hall control; The motor/controller is installed integrally.

Product C: Surface-mounted External Rotor DC brushless motor+square wave controller; No communication control, no sense control; The motor/controller is installed integrally.

 Surface-mounted External Rotor DC brushless motor.png

The rated efficiency of Model A motor is 81.7%, and the rotating speed can be stabilized between 460 revolutions. The matching problem between the controller and hall element causes the motor to shake obviously during operation.


The rated efficiency of model B motor is 83%, and its LOGO is "internationally famous manufacturer". The motor integrates temperature and humidity sensors, wireless modules, etc. and has a good product concept.


The rated efficiency of model C motor is ≈84.8%. During the test, the motor cannot be loaded to the rated load of 750W, and the rotation speed of the motor keeps decreasing during the loading process (the rotation speed of the fan decreases from 460 to 420, and the air volume loss is 9%). This type of motor is modified from the electric motor of the two-wheel battery car, with more than 40 poles and great interference in operation. The dead weight of the motor body, including the fan blades, generates a certain radial force, which is borne by the bearing with an inner diameter of φ15, thus causing great structural instability.


The above-mentioned three Chinese-made DC brushless motors for negative pressure fans can obtain certain market feedback in the negative pressure fans (industrial ventilation market), which is a good sign of the transformation of Chinese negative pressure fan manufacturers to high performance. We have more reason to believe that in this transformation process, the above-mentioned motor manufacturers will continue to improve their products, making the products have better performance and better meet the actual needs of negative pressure fans.

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