What is the difference between a brushless DC motor and a DC brushed motor?

2021-11-19 10:50

There are more and more applications of brushless DC motors in the electric vehicle industry. I believe that many friends are still quite vague about the difference between brushless DC motors and brushed DC motors. Now I will explain the difference between them.

The difference between a brushless DC motor and a brushed motor is whether it is equipped with a commonly used brush-commutator. The commutation of a brushed DC motor has always been achieved by the graphite brush and the ring commutator installed on the rotor. The brushless DC motor uses the Hall sensor to feed back the rotor position to the control circuit, so that it can know the exact time of the motor phase commutation. Most brushless motor manufacturers have three Hall effects. The positioning sensor, because the brushless motor has no brushes, there is no related interface, so it is cleaner, less noise, in fact, does not require maintenance, and has a longer life.

In summary, the performance of brushless DC motors is better than brushed DC motors. With the continuous improvement of electric vehicle manufacturing technology, brushless DC motors will also be widely used.

The difference between brushed motor and brushless motor

The difference between the two

1. When the motor with brush motor is working, the coil and commutator rotate, the magnetic steel and carbon brush do not rotate, and the alternating change of the coil current direction is completed by the commutator and brush that rotate with the motor.

2. The brushless DC motor is composed of the motor main body and the driver, which is a typical mechatronics product. Because the brushless DC motor runs in a self-control mode, it will not add a start winding to the rotor like a synchronous motor that is started under heavy load under variable frequency speed regulation, nor will it cause oscillation and out-of-step when the load changes suddenly.

3. The brush motor is a traditional product with relatively stable performance. The brushless motor is an upgraded product, and its life performance is better than that of the brush motor. However, its control circuit is more complicated, and the requirements for aging and screening of components are stricter.

4. Brushless motor equipment can be used in: dairy industry, brewing industry, meat processing industry, soy product processing industry, beverage processing industry, pastry processing industry, pharmaceutical industry, electronic precision factory, etc. Dust workshops, such as the brushless motor (DIHOUR) hand dryer produced by Dior Electric, are used in factories.

5. Carbon brush motors can only be used in areas where the requirements are not too high, such as various toilets, but they cannot be used in dust-free workshops and explosion-proof workshops!


Other differences

1. Scope of application

Brushless motor: usually used in equipment with relatively high control requirements and high speed, such as airplanes, precision instruments and meters, which have strict control of motor speed and high speed.

Carbon brush motors: usually brush motors are used in power equipment, such as hair dryers, factory motors, household range hoods, etc. In addition, the speed of the series motor can also reach very high, but due to the wear of the carbon brushes, use The service life is not as good as the brushless motor.

2. Service life

Brushless motor: Usually the service life is in the order of tens of thousands of hours, but the service life of brushless motors is also very different due to different bearings.

Carbon brush motor: Generally, the continuous working life of brush motor is several hundred to more than 1,000 hours. When the use limit is reached, the carbon brush needs to be replaced, otherwise it is easy to cause the wear of the bearing.

3. Use effect

Brushless motor: usually digital frequency conversion control, strong controllability, from a few revolutions per minute to tens of thousands of revolutions per minute can be easily achieved.

Carbon brush motor: The old carbon brush motor generally works at a constant speed after startup, and speed regulation is not easy. The series motor can also reach 20,000 rpm, but the service life will be relatively short.

4. Energy saving

Relatively speaking, the brushless motor controlled by inverter technology will save much energy than the series motor. The most typical ones are inverter air conditioners and refrigerators.

5. Future maintenance

The carbon brush motor needs to be replaced. If it is not replaced in time, the motor will be damaged. The brushless motor has a long service life, usually more than 10 times that of the brush motor. However, if it is broken, the motor needs to be replaced, but the daily maintenance is basic unnecessary.

Reference: Baidu Encyclopedia Brushless Motor Baidu Encyclopedia Brushless Motor

6. Service life, the brushless motor can work continuously for about 20,000 hours, and the conventional service life is 7-10 years. Carbon brush motor: It can work continuously for about 5000 hours, and the normal service life is 2-3 years.

7. In terms of energy saving, relatively speaking, the power consumption of brushless motors is only 1/3 of that of carbon brushes.

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