Today to share the difference between brushed and brushless motors, first we understand the classification of the motor!
The original motor is also divided into DC motor, AC motor, and brushless motor, brush motor is divided into DC motor category, then the question arises, the same category of brushless, brush what is the difference?
Distinguish from the working principle
Brushless DC motor mainly consists of a rotor made of permanent magnet material, a stator with coil winding and a position sensor (optional)!
A brushless DC motor consists of a motor body and a driver, and is a typical mechatronic product. Since brushless DC motors operate in a self-controlled manner, they do not have another starting winding on the rotor like synchronous motors with heavy load starting under frequency regulation, nor do they oscillate and lose step when the load changes suddenly.
Brushless is a brush motor without “brushes”, the role of brushes in a brush motor is to energize the coil in the rotor through the commutator.
After watching the above two videos on brushless and brush motors have a deeper understanding of it? Then I ask again, how does a motor without brushes energize the coil in the rotor?
It turns out that brushless motors use permanent magnets to make the rotor, and there is no coil in the rotor. Since there is no coil in the rotor, there is no need for commutator and brushes for energizing the rotor. Instead, the coil is used as the stator. (As shown in the figure below)
The origin of brushless motors is also relatively simple from the beginning: most of the problems with brushed DC motors come from the brushes.
Brushes can spark, wear out, make a lot of noise and generate a large percentage of power consumption, resulting in severely limited speed and not being easily cooled.
This means you can’t use brushed DC motors around anything flammable, in applications where long life, silence or high efficiency are required, or in any high-speed or high-power system.
These are significant drawbacks to brushes, and eliminating them solves these problems, but the downside is that it also eliminates mechanical commutation.
The lack of mechanical commutation can cause other problems because the motor needs to be commutated. Brushless motors use electrical commutation, and with this type of commutation, you need to make sure that the current in the motor always produces a magnetic field that moves the rotor.
But look at the diagram below, you need to know where the rotor is before you can consider how to apply current to move the rotor.
The coils do not move, the poles rotate. Brushless DC motors, through Hall elements, sense the position of the magnetic poles of the permanent magnets and, based on this sense, use electronic circuits to switch the direction of the current in the coil at the right time to ensure that the correct direction of magnetic force is generated to drive the motor.
With less brushes, the wear and tear of brushless DC motors is mainly on the bearings. From the mechanical point of view, brushless DC motors are almost a maintenance-free motor, and only some dust removal maintenance is needed when necessary.
The main difference between the brushless dc motors and brushed dc motors
1.When the brush motor works, the coil and commutator rotate, the magnet and carbon brush do not rotate, the alternate change of coil current direction is done by the commutator and brush which rotate with the motor.
2.Brushless DC motor is composed of motor body and driver, which is a typical mechatronic product. Since the brushless DC motor runs in self-control, it will not add another starting winding on the rotor like the synchronous motor that starts under heavy load under frequency regulation, and it will not produce oscillation and lost step when the load changes suddenly.
3.Brush motor is a traditional product, the performance is more stable. Brushless motor is an upgraded product, and its life performance is better than brush motor. However, its control circuit is more complex, and the aging screening requirements for components are more stringent.
4.Brushless motor equipment can be used in: dairy industry, brewing industry, meat processing industry, soybean processing industry, beverage processing industry, pastry processing industry, pharmaceutical industry, electronic precision factory, and some higher requirements of the clean room, such as Dior electrical production brushless motor (DIHOUR) hand dryer, used in the factory more.
5. Carbon brush motor can only be applied to a variety of restrooms and other areas that are not too demanding, and like the clean room and explosion-proof workshop can not be used!
6. Service life, brushless motor can work continuously for about 20000 hours, the conventional service life of 7-10 years. Carbon brush motor: can work continuously for about 5,000 hours, the conventional service life of 2-3 years.
7. Energy saving, relatively speaking, the power consumption of brushless motor is only 1/3 of carbon brush.
Brushless dc motors and brushed motors performance comparison
1.Friction, loss of some friends in the brush motor often encounter this problem, that is, after using the motor for a period of time, the need to open the motor to clean up the motor brush, time-consuming and laborious, maintenance intensity is no less than a household cleaning.
2.Heat, short life due to the structure of the brush motor, brush and commutator contact resistance is very large, resulting in the overall resistance of the motor, easy to heat, and permanent magnets are heat-sensitive components, if the temperature is too high, the magnets will demagnetize, so that the motor performance decreases, affecting the life of the brush motor.
3.Low efficiency, low output power above the brush motor heating problem, largely because the current work in the motor internal resistance, so a large degree of electrical energy into heat, so the output power of brush motor is not large, and efficiency is not high.
The advantages of brushless motor
1.Low interference brushless motor in addition to brushed motor, the most direct change is no brush motor operation generated by electric sparks, which greatly reduces the interference of electric sparks on remote control radio equipment.
2.Low noise, smooth operation brushless motor without brushes, friction is greatly reduced when running, smooth operation, noise will be much lower, this advantage for the model running stability is a huge support.
3.Long life, low maintenance costs less brushes, brushless motor wear is mainly in the bearings, from a mechanical point of view, brushless motor is almost a maintenance-free motor, when necessary, only need to do some dust maintenance can be.
Up and down a comparison, you know where the advantages of brushless motor compared to brush motor, but everything is not absolute, brush motor low-speed torque performance, torque and other performance characteristics are irreplaceable brushless motor, but on the ease of use of brushless motor, with the cost of brushless controller downward trend and the development of brushless technology at home and abroad and market competition, which also greatly promote the domestic The development of brushless motor.
From the trend, brushless motor speed may replace the brushed dc geared motors
1.The scope of application: brushless motor: usually used in the control requirements are relatively high, the speed is relatively high on the equipment, such as models, precision instruments and other strict control of motor speed, speed up to a very high equipment vendors, in addition to the most advanced hand dryer, the cost of the motor and controller are very high, so also after the more high-end equipment to be used.
Carbon brushed motor: usually power equipment used are brushed motors, such as hair dryers, factory electric motors, household range hoods and so on, in addition to series excitation motor speed can also reach very high, but due to the wear and tear of carbon brushes, service life is not as long as brushless motors.
2.Service life brushless motor: usually the service life in the order of tens of thousands of hours, but due to the different bearings brushless motor service life is also very different. Brush motor: usually brushed motor continuous working life of a few hundred to more than 1,000 hours, reaching the limit of use will need to replace the carbon brush, otherwise it is easy to cause wear and tear of the bearings.
3.The use of effect brushless motor: usually digital frequency control, controllable, from a few revolutions per minute, to tens of thousands of revolutions per minute can be easily achieved. Carbon brushed motor: brushless motors generally start after the work speed is constant, speed regulation is not very easy, series excitation motor can also reach 20000 rpm, but the service life will be relatively short.
4.Energy saving and environmental protection, relatively speaking, brushless motor using frequency conversion technology control will be a lot more energy efficient than series excitation motor, the most typical is the frequency conversion air conditioners and refrigerators.
5.The future maintenance of carbon brushed motor needs to replace the carbon brush, if the replacement is not timely will cause damage to the motor, and brushless dc motor, the service life is very long, usually more than 10 times the brushed motor, but bad need to replace the motor, but the basic routine maintenance is not required.
6.The noise aspect of the noise and whether it is brushed motor has nothing to do with, mainly depends on the bearing and click the internal components of the fit.
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