Brushless electric power and motor knowledge

Electric aircraft power, mainly refers to two components:

The first is the motor (Motor), also known as motor.

The second is to control the motor speed governor (Speed ​​Controller), a long time ago the governor is the use of steering gear control adjustable resistance to achieve, such as mechanical governor, is now out of the stage of history, Only in some re-carved frame box or brochure to see their photos. Now we say that the governor, refers to the electronic governor, referred to as ESC, English Electronic Speed ​​Controller, abbreviated ESC

According to the class to points, can be divided into brush power and brushless power. That is, brush with a brush motor brush, and brushless motor with brushless motor.

Brush motor and brushless motor

Car models with the motor, all the internal rotor motor, which is the motor shell is fixed, by the inside of the circular rotor rotation. Outside the rotor here is not discussed, want to know the outer rotor and the inner rotor, you can understand their own Baidu.

Brush motor: early motor, the magnet is fixed in the motor shell or base, as the stator. And then the coil winding, a rotor, model car brush motor are common are three groups of wire, the figure is a typical brush motor structure. The same time as

In addition to the stator, the rotor, and the carbon brush, the brush motor is also called the carbon brush motor, or the carbon brush motor. The carbon brush is brought into contact with the copper head on the winding to allow the motor to rotate. However, due to high-speed rotation, will bring the carbon brush wear, so brush the motor needs to run out after the carbon brush, replace the carbon brush. And copper head will wear, so in the era of carbon brush competition motor, in addition to the replacement of carbon brush, but also need to polish the copper head, so that the copper head to keep smooth. Replace the carbon brush also need to run, so that the carbon brush and copper head contact area to maximize the maximum current to improve the motor speed / torque.

Brushless motor: Since there are more than the drawbacks of the brush, so brushless came into being.

Brushless is the coil around the stator, and then the magnet made of the rotor, rotating the magnet, not the coil, so there is no carbon brush this consumable.

Since the coil is fixed, how do you make the coil change the magnetic field? This is why brushless requires three lines. With the brushless ESC, the coil group corresponding to the power supply to produce the corresponding magnetic field, you can continue to drive the magnet rotor to keep rotating.

The following figure is the most basic principle of brushless motor, animation is very easy to understand, that is, we are now the mainstream 2-pole motor drive principle.

Summary: whether brush motor or countless motor, the basic principle is generated by the coil magnetic field, and then with the permanent magnet to drive the rotor rotation. Brush is made of permanent magnet stator, coil made of rotor. While the brush is made of the stator stator, permanent magnet made of circular rotor.

Motor tips: players facing the motor output shaft, the motor counterclockwise rotation, the frame is the direction of the forward, it is the standard frame design. If some frames use non-standard design, then it will become a motor counterclockwise rotation, the car but back. Of course, there may be some axle player installation process error, the difference between the right and wrong, there will be reverse error.

Brushing and brushless telemetry

Brush electric transfer, finished brush motor, naturally have to mention the brush electric transfer, brush electric adjustment is used to control the brush motor speed of the equipment.

Brush electric tuning is often only four lines, two are input power side, received positive and negative. The other two are the output of the motor speed control, connected to the two electrodes on the motor. By changing the current / voltage and conduction direction can be achieved on the speed and positive and negative control.

The following figure is a good cool cool running 60A waterproof brush electric transfer

The previous top-level brush-level brush is not reversing, so there are only three studs, the positive pole of the motor and the positive pole of the battery are the same.

Brushless, and brush the same reason, brushless motor needs to work, it is necessary to have a brushless ESC.

Brushless ESC input is the same as two lines, positive and negative power supply. But brushless output requires three lines. Principle We introduced the brushless motor when we said, is to rely on three lines to change the magnetic field to drive the rotor rotation.

The following figure is the current good surplus V3.1 version 120A ESC

Having finished the principle, we know that brushless motor must use brushless electric tone can. While the brush motor will need to use brush electric tone Caixing. But some brushless ESC can be rewritten through the built-in procedures, so that the output of the three line bridge made of two, to drive the brush motor. Good surplus technology has been launched before such products, but already discontinued because brushless has become the mainstream.

Finished the basic principles, the following are some of the basic parameters of the motor and its significance

Motor common parameters: T number, speed, brushless motor KV value, size, shaft diameter, 2 pole / 4 pole is what, feeling and no sense of what?

Motor T number:

T, English Turn, the number of turns around the coil, such as coil around 21 laps, called 21T. Some brands are also known as R, Round abbreviations, the same meaning, are the number of coils around.

Brush the motor because the winding is from the copper head, and then also in the copper head at the end, so the brush is an integer circle, such as 20T, 30T and so on.

Brushless motor because of structural constraints, are common from the input end, the end of the other side, so the common are mostly half, so most of them are 4.5,8.5,21.5 T this. There are also some structures that are special for integer circles, such as 4T. This integer circle is relatively small.

Regardless of brush or brushless, with the same series of the same size, the coil is the smaller, the greater the motor speed and torque, power and heat the higher, can provide more powerful power output. Previously we have noticed a lot of online circulation, said T number of high motor, torque is much lower than the T number. This is a complete misunderstanding. The T number of the motor is similar to the displacement of the real car. The smaller the T number is, the higher the displacement and the greater the power and torque. Choose what number of T, it is based on the needs of the problem, but also involves the gear ratio with.

Brushless motor and brush motor T number between the corresponding relationship: often we think brushless motor T number, multiplied by 2 to 2.5, the resulting value, the number of T number of brush, with this no The power of the brush T is close to the torque. For example, a 8.5T brushless, about 17 ~ 21T between the brush close; and then for example, a 21.5T brushless, with a 43 ~ 55T between the brush close.

Speed ​​/ KV value:

Some of the brush motor will mark the speed, such as 30000rpm @ 7.2V, meaning it is 7.2V when the motor can achieve 30,000 rpm per minute no-load speed.

Brushless motor is the standard KV value, brushless KV value is unique brushless, refers to the voltage for each additional 1V, the motor speed increase the number of RPM, for example, 3000KV meaning for each increase in voltage 1V can increase the motor speed 3000RPM , So we can convert the motor in 8.4V full charge of lithium, the speed is 8.4 * 3000 = 25200RPM

Brushless motor but a good, its T number and KV value is fixed, for example, a brand of a model of 8.5T is 4000KV, 10.5T is 3300KV this. So brushless motor in the sales of some will only T number, or only standard KV value, not all models will be marked with T number and KV value, but in the specification parameters of these two basic will not be absent.

The number of T, mainly 3650 of the motor, while the other types of the main standard KV value. This is an international practice related to the problem.

Output shaft diameter:

The motor needs to drive the car to turn, to output power, naturally need to rely on the output of the shaft to install the motor teeth or drive shaft, so the size of the output shaft has become a must consider the factors.

Common shaft diameter: 2mm, 3.175mm, 5mm, 8mm

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