One of the reasons why designers are interested in brushless electric motors is the need for high-speed motors with small dimensions. Moreover, these motors have very precise positioning. The design has a movable rotor and a fixed stator. There is one permanent magnet on the rotor or several located in a certain sequence. On the stator, there are coils that create a magnetic field.
One more feature should be noted - brushless motors can have an anchor located both inside and on the outside. Consequently, the two types of construction can have specific applications in different fields. When the anchor is located inside, it turns out to achieve a very high rotation speed, therefore, such motors work very well in the design of cooling systems. In the event that an external rotor drive is installed, very precise positioning can be achieved as well as high overload resistance. Very often, such motors are used in robotics, medical equipment, and frequency-controlled machine tools.
How motors work
In order to set in motion the rotor of a brushless DC motor, a special microcontroller must be used. It cannot be started in the same way as a synchronous or asynchronous machine. With the help of a microcontroller, it turns out to turn on the motor windings so that the direction of the vectors of the magnetic fields on the stator and the armature are orthogonal.
In other words, with the help of a driver, it turns out to regulate which acts on the rotor of a brushless motor. To move the armature, it is necessary to carry out correct commutation in the stator windings. Unfortunately, smooth rotation control is not possible. But you can very quickly increase the rotor of the electric motor.
Differences between brushed and brushless motors
The main difference is that there is no winding on the rotor on brushless motors for models. In the case of collector motors, there are windings on their rotors. But permanent magnets are installed on the stationary part of the engine. In addition, a collector of a special design is installed on the rotor, to which the graphite brushes are connected. With their help, voltage is supplied to the rotor winding. The principle of operation of a brushless electric motor is also significantly different.
How the collector machine works
To start the collector motor, you will need to apply voltage to the excitation winding, which is located directly on the armature. In this case, a constant magnetic field is formed, which interacts with the magnets on the stator, as a result of which the armature and the collector attached to it rotate. In this case, power is supplied to the next winding, the cycle is repeated.
The rotor speed depends directly on how intense the magnetic field is, and the latter characteristic depends directly on the magnitude of the voltage. Therefore, in order to increase or decrease the speed, it is necessary to change the supply voltage.
To implement reverse, you only need to change the polarity of the motor connection. For such control, you do not need to use special microcontrollers; you can change the speed using a conventional variable resistor.
Features of brushless machines
But control of a brushless electric motor is impossible without the use of special controllers. Based on this, we can conclude that motors of this type cannot be used as a generator. For efficient control, the position of the rotor can be monitored using multiple Hall sensors. With the help of such simple devices, it is possible to significantly improve the characteristics, but the cost of the electric motor will increase several times.
Brushless motors start
It makes no sense to make microcontrollers on your own, a much better option would be to buy a ready-made, albeit Chinese one. But you must adhere to the following recommendations when choosing:
- Observe the maximum permissible current. This parameter will definitely come in handy for various types of drive operation. The characteristic is often indicated by manufacturers directly in the name of the model. Very rarely, the values are indicated, typical for peak modes, in which the microcontroller cannot work for a long time.
- For continuous operation, the maximum supply voltage must also be taken into account.
- Be sure to consider the resistance of all internal microcontroller circuits.
- It is imperative to take into account the maximum number of revolutions that is typical for the operation of this microcontroller. Please note that it will not be able to increase the maximum speed, as the limitation is made at the software level.
- Cheap models of microcontroller devices have pulses in the range of 7 ... 8 kHz. Expensive copies can be reprogrammed, and this parameter is increased by 2-4 times.
Try to select microcontrollers in all respects, as they affect the power that an electric motor can develop.
How is it managed
The electronic control unit allows the commutation of the drive windings. To determine the moment of switching using the driver, the rotor position is monitored by a Hall sensor installed on the drive.
In the event that there are no such devices, it is necessary to read the reverse voltage. It is generated in the stator coils that are not currently connected. The controller is a hardware and software complex, it allows you to track all changes and set the switching order as accurately as possible.
Three-phase brushless motors
A lot of brushless electric motors for aircraft models are powered by direct current. But there are also three-phase instances in which converters are installed. They make it possible to make three-phase pulses from a constant voltage.
The work takes place as follows:
- Coil "A" receives pulses with a positive value. To coil "B" - with a negative value. As a result, the anchor will begin to move. The sensors fix the offset and a signal is sent to the controller for the next commutation.
- Coil "A" is disconnected, and a positive impulse is applied to the winding "C". The commutation of the "B" winding does not undergo any changes.
- Coil "C" receives a positive impulse, and negative impulse goes to "A".
- Then the pair "A" and "B" comes into operation. They are supplied with positive negative pulse values, respectively.
- Then a positive impulse goes back to coil "B", and a negative impulse to "C".
- At the last stage, coil "A" is switched on, to which a positive pulse is received, and a negative one goes to C.
And after that, the whole cycle is repeated.
Benefits of using
It is difficult to make a brushless electric motor with your own hands, and it is almost impossible to implement microcontroller control. Therefore, it is best to use ready-made industrial designs. But be sure to consider the advantages that the drive receives when using brushless motors:
- Significantly longer resource than collector machines.
- High level of efficiency.
- The power is higher than that of brushed motors.
- The rotational speed picks up much faster.
- No sparks are generated during operation, so they can be used in environments with a high fire hazard.
- Very easy operation of the drive.
- When working, you do not need to use additional components for cooling.
Among the disadvantages, one can single out a very high cost, if we also take into account the price of the controller. Even briefly turning on such an electric motor to check its operability will not work. In addition, repairing such motors is much more difficult due to their design features.
The principle of operation of a brushless DC motor (BKDP) has been known for a very long time, and brushless motors have always been an interesting alternative to traditional solutions. Despite this, such electric machines found widespread use in technology only in the 21st century. The decisive factor in the widespread implementation was the multiple reduction in the cost of the drive control electronics of the BDKP.
Collector motor problems
At a fundamental level, the job of any electric motor is to convert electrical energy into mechanical energy. There are two main physical phenomena that underlie the design of electrical machines:
The motor is designed in such a way that the magnetic fields generated on each of the magnets always interact with each other, giving the rotor rotation. A traditional DC motor has four main parts:
- stator (stationary element with a ring of magnets);
- armature (rotating element with windings);
- carbon brushes;
- collector.
This design provides for the rotation of the armature and the collector on the same shaft relative to the stationary brushes. The current flows from the source through the brushes spring-loaded for good contact to the commutator, which distributes the electricity between the armature windings. The magnetic field induced in the latter interacts with the stator magnets, which causes the stator to rotate.
The main disadvantage of the traditional motor is that mechanical contact on the brushes cannot be achieved without friction. As the speed increases, the problem manifests itself more strongly. The manifold assembly wears out over time and is also prone to arcing and can ionize the surrounding air. Thus, despite the simplicity and low cost to manufacture, such electric motors have some insurmountable disadvantages:
- wear of brushes;
- electrical interference due to arcing;
- maximum speed limits;
- difficulties with cooling a rotating electromagnet.
The advent of processor technology and power transistors allowed designers to abandon the mechanical switching unit and change the role of the rotor and stator in a DC electric motor.
The principle of operation of the BDKP
In a brushless electric motor, unlike its predecessor, an electronic converter plays the role of a mechanical switch. This makes it possible to carry out the "turned inside out" scheme of the BDKP - its windings are located on the stator, which eliminates the need for a collector.
In other words, the main fundamental difference between the classic motor and the BDKP is that instead of stationary magnets and rotating coils, the latter consists of stationary windings and rotating magnets. Despite the fact that the switching itself in it occurs in a similar way, its physical implementation in brushless drives is much more complicated.
The main issue is the precise control of the brushless motor, assuming the correct sequence and frequency of switching individual sections of the windings. This problem is constructively solvable only if it is possible to continuously determine the current position of the rotor.
The data required for processing by the electronics is obtained in two ways.:
- detection of the absolute position of the shaft;
- by measuring the voltage induced in the stator windings.
To implement control in the first way, either optical pairs or Hall sensors fixed to the stator, which react to the rotor magnetic flux, are most often used. The main advantage of such systems for collecting information about the position of the shaft is their performance even at very low speeds and at rest.
Sensorless control to estimate the voltage in the coils requires at least a minimum rotor rotation. Therefore, in such designs, a mode is provided for starting the engine up to revolutions, at which the voltage on the windings can be estimated, and the quiescent state is tested by analyzing the effect of the magnetic field on the test current pulses passing through the coils.
Despite all the above design difficulties, brushless motors are gaining more and more popularity due to their performance and characteristics that are inaccessible to the collector. A short list of the main advantages of the BDKP over the classic ones looks like this:
- no mechanical energy loss due to brush friction;
- comparative noiselessness of work;
- easy acceleration and deceleration due to low rotor inertia;
- precise rotation control;
- the possibility of organizing cooling due to thermal conductivity;
- ability to work at high speeds;
- durability and reliability.
Modern application and perspectives
There are many devices for which increasing uptime is critical. In such equipment, the use of BDKP is always justified, despite their relatively high cost. These can be water and fuel pumps, turbines for cooling air conditioners and engines, etc. Brushless motors are used in many models of electric vehicles. Nowadays, the automotive industry is seriously focusing on brushless motors.
BDKP are ideal for small drives operating in difficult conditions or with high accuracy: feeders and belt conveyors, industrial robots, positioning systems. There are areas in which brushless motors dominate uncontested: hard drives, pumps, silent fans, small appliances, CD / DVD drives. Low weight and high power output have made the BDKP also the basis for the production of modern cordless hand tools.
We can say that there is significant progress in the field of electric drives. The continuing decline in the price of digital electronics has given rise to a trend towards widespread use of brushless motors to replace traditional ones.
This article describes in detail the process of rewinding an electric brushless motor at home. At first glance, this process may seem laborious and time-consuming, but if you figure it out, one rewinding of the engine will take no more than an hour.
The engine got under the rewind
Materials (edit):
- Wire (0.3 mm)
- Varnish
- Heat shrink (2 mm and 5 mm)
Instruments:
- Scissors
- Nippers
- Soldering iron
- Solder and acid
- Sandpaper (file)
- Lighter
Step 1. Prepare the motor and wire.
Remove the lock washer from the motor shaft and take out the stator.
We wind up the old winding from the stator. I recommend counting the number of turns per tooth. The diameter of the old wire can be found by winding 10 turns on a pencil, measure the width of this winding with a ruler and divide by 10.
We carefully examine the stator teeth for abrasions of the protective enamel. If necessary, cover them with varnish (you can even use nail varnish).
With a felt-tip pen or a marker for disks, we number the stator teeth so as not to confuse and not wind the wire on the wrong tooth.
In this case, a wire with a diameter of 0.3 mm will be wound in two cores with 16 turns per tooth. This is about 50 cm of double-folded wire per tooth + 20 cm for leads.
Since one wire is wound on 4 teeth with two leads, and there are only 12 teeth, we need three double wires about 2.5 meters long. Better to let it be with a margin than not enough a couple of turns for the last tooth.
Step 2. Wrapping the stator teeth.
The wrapping will be divided into three stages, according to the number of wires. In order not to get confused in the leads of the wires, you can mark them with pieces of electrical tape or plaster with inscriptions.
I deliberately do not attach separate photographs of each wrapped tooth - much more will be said and shown in color schemes.
Wire # 1:
Winding scheme
Leave about 10 cm of wire to create the lead (S1).
We wind the first wire (orange in the diagram) on the tooth №2 clockwise arrow. The denser and smoother the turns, the more turns will fit on the stator teeth.
After we have wound 16 turns, we lay the wire to the tooth №1 and reel counter-clockwise arrows are also 16 turns.
№7 and wind 16 turns clockwise arrow.
№8 and wind 16 turns counter-clockwise arrows.
Leave 10 cm of wire to create the lead (E1), the rest can be cut off.
That's it, the first wire is wound.
Wire number 2:
Winding scheme
Leave about 10 cm of wire to create the lead (S2).
We wind 16 turns of the second wire (green in the diagram) on the tooth №6 clockwise arrow.
We lay the wire to the tooth №5 and wind 16 turns counter-clockwise arrows.
Then we stretch the wire to the tooth №11 and wind 16 turns clockwise arrow.
Then we lay the wire to the tooth №12 and wind 16 turns counter-clockwise arrows.
Leave 10 cm of wire to create the lead (E2), cut off the rest.
The second wire is wound.
Wire # 3:
Winding scheme
Leave about 10 cm of wire to create the lead (S3).
We wind 16 turns of the second wire (blue in the diagram) on the tooth №10 clockwise arrow.
We lay the wire to the tooth №9 and wind 16 turns counter-clockwise arrows.
Then we stretch the wire to the tooth №3 and wind 16 turns clockwise arrow.
Then we lay the wire to the tooth №4 and wind 16 turns counter-clockwise arrows.
Leave 10 cm of wire to create the lead (E3), cut off the rest.
The third wire is wound.
Step 3. Connecting the winding leads.
Connection diagram
Conclusion S1 and E2 (teeth №2 and №12 ) we twist at the base of the teeth, making the tail 5-7 cm long.
Similarly, we twist pins S2 and E3 (teeth №6 and №4 ), as well as conclusions S3 and E1 (teeth №10 and №8 )
We stretch a thin heat shrink along the entire length and to the very base on the terminals. Then gently heat it up with a lighter.
We collect the resulting three pins together and tighten them with heat shrinkage of a larger diameter, pulling it also to the very base.
Household and medical equipment, aircraft modeling, pipe shut-off drives for gas and oil pipelines - this is not a complete list of applications for DC brushless motors (DB). Let's take a look at the design and operation of these electromechanical actuators in order to better understand their advantages and disadvantages.
General information, device, scope
One of the reasons for the growing interest in OBDs is the increased demand for high-speed micromotors with precise positioning. The internal structure of such drives is shown in Figure 2.
Rice. 2. The device of the brushless motorAs you can see, the structure is a rotor (armature) and a stator, the first has a permanent magnet (or several magnets arranged in a certain order), and the second is equipped with coils (B) to create a magnetic field.
It is noteworthy that these electromagnetic mechanisms can be both with an internal armature (this type of construction can be seen in Figure 2), and external (see Fig. 3).
Rice. 3. Outrunner design Accordingly, each of the designs has a specific field of application. Devices with an internal armature have a high rotation speed, therefore they are used in cooling systems, as power plants for drones, etc. External rotor drives are used wherever precise positioning and torque resistance are required (robotics, medical equipment, CNC machines, etc.).
Principle of operation
Unlike other drives, for example, an asynchronous AC machine, a special controller is required for the operation of the OBD, which turns on the windings in such a way that the vectors of the magnetic fields of the armature and stator are orthogonal to each other. That is, in fact, the driver device regulates the torque acting on the OBD armature. This process is clearly demonstrated in Figure 4.
As you can see, for each movement of the armature, it is necessary to perform a certain commutation in the stator winding of a brushless motor. This principle of operation does not allow smooth control of rotation, but it makes it possible to quickly gain momentum.
Differences between brushed and brushless motors
The collector-type drive differs from the DB both in design features (see Fig. 5.) and in the principle of operation.
Rice. 5.A - brushed motor, B - brushless Consider the design differences. Figure 5 shows that the rotor (1 in Fig. 5) of a collector-type motor, unlike a brushless one, has coils with a simple winding circuit, and permanent magnets (usually two) are installed on the stator (2 in Fig. 5 ). In addition, a collector is installed on the shaft, to which brushes are connected, which supply voltage to the armature windings.
Let's briefly talk about the principle of operation of collector machines. When voltage is applied to one of the coils, it is excited and a magnetic field is generated. It interacts with permanent magnets, this makes the armature and the collector located on it turn. As a result, power is supplied to the other winding and the cycle repeats.
The rotation frequency of an armature of this design directly depends on the intensity of the magnetic field, which, in turn, is directly proportional to the voltage. That is, in order to increase or decrease the speed, it is enough to increase or decrease the level of nutrition. And to reverse it is necessary to switch the polarity. This method of control does not require a special controller, since the speed controller can be made on the basis of a variable resistor, and a conventional switch will work as an inverter.
We discussed the design features of brushless motors in the previous section. As you remember, their connection requires a special controller, without which they simply will not work. For the same reason, these motors cannot be used as a generator.
It is also worth noting that in some actuators of this type, for more efficient control, the rotor positions are monitored using Hall sensors. This significantly improves the characteristics of brushless motors, but leads to an increase in the cost of an already expensive design.
How to start a brushless motor?
To get this type of drive to work, a dedicated controller is required (see Figure 6). Without it, launch is impossible.
Rice. 6. Brushless motor controllers for modeling It makes no sense to assemble such a device yourself, it will be cheaper and more reliable to purchase a ready-made one. It can be selected according to the following characteristics inherent in PWM channel drivers:
- The maximum permissible current, this characteristic is given for the normal operation of the device. Quite often, manufacturers indicate such a parameter in the model name (for example, Phoenix-18). In some cases, a value is given for the peak mode, which the controller can maintain for a few seconds.
- Maximum nominal voltage for continuous operation.
- Resistance of the controller's internal circuits.
- The permissible speed is indicated in rpm. Above this value, the controller will not allow increasing the rotation (the limitation is implemented at the software level). Please note that the speed is always given for 2-pole drives. If there are more pole pairs, the value should be divided by their number. For example, the number 60,000 rpm is indicated, therefore, for a 6-magnetic motor, the rotational speed will be 60,000 / 3 = 20,000 prm.
- The frequency of the generated pulses, for most controllers, this parameter ranges from 7 to 8 kHz, more expensive models allow you to reprogram the parameter by increasing it to 16 or 32 kHz.
Note that the first three characteristics determine the power of the OBD.
Brushless motor control
As already mentioned above, the switching of the drive windings is electronically controlled. The driver monitors the armature position using Hall sensors to determine when to switch. If the drive is not equipped with such detectors, then the back EMF that occurs in the unconnected stator coils is taken into account. The controller, which is, in fact, a hardware and software complex, monitors these changes and sets the switching order.
Three-phase brushless DC motor
Most of the OBDs are made in a three-phase design. To control such a drive, the controller has a DC-to-three-phase pulse converter (see Fig. 7).
Figure 7. DB voltage diagrams To explain how such a valve motor works, one should consider Figure 4 along with Figure 7, where all the stages of the drive operation are shown in turn. Let's write them down:
- A positive impulse is applied to coils "A", while a negative impulse is applied to "B", as a result the armature will move. The sensors will record its movement and give a signal for the next commutation.
- Coil "A" turns off, and a positive pulse goes to "C" ("B" remains unchanged), then a signal is sent to the next set of pulses.
- On "C" - positive, "A" - negative.
- The pair "B" and "A" are working, which receive positive and negative impulses.
- A positive impulse is reapplied to "B", and a negative impulse to "C".
- Coils "A" are turned on (+ is supplied) and a negative impulse to "C" is repeated. Then the cycle is repeated.
There are a lot of difficulties in the seeming simplicity of control. It is necessary not only to track the position of the armature in order to produce the next series of pulses, but also to control the speed by adjusting the current in the coils. In addition, you should select the most optimal parameters for acceleration and deceleration. It is also worth not forgetting that the controller must be equipped with a block that allows you to control its operation. The appearance of such a multifunctional device can be seen in Figure 8.
Rice. 8. Multifunctional brushless motor controller Advantages and disadvantages
An electric brushless motor has many advantages, namely:
- The service life is significantly longer than that of conventional collector counterparts.
- High efficiency.
- Rapid set of maximum rotation speed.
- It is more powerful than CD.
- The absence of sparks during operation allows the drive to be used in fire hazardous conditions.
- No additional cooling required.
- Simple operation.
Now let's look at the cons. A significant drawback that limits the use of databases is their relatively high cost (taking into account the price of the driver). Among the inconveniences is the impossibility of using the database without a driver, even for a short-term turn-on, for example, to check the operability. Problematic repairs, especially if rewinding is required.
Engines are used in many areas of technology. In order for the motor rotor to rotate, a rotating magnetic field must be present. In conventional DC motors, this rotation is carried out mechanically by means of brushes sliding over a manifold. This creates sparks and, in addition, due to the friction and wear of the brushes, these motors require constant maintenance.
Thanks to the development of technology, it has become possible to generate a rotating magnetic field electronically, which has been embodied in brushless direct current motors (BDCM).
Device and principle of operation
The main elements of the BDPT are:
- rotor on which permanent magnets are attached;
- stator on which the windings are installed;
- electronic controller.
By design, such an engine can be of two types:
with an internal rotor (inrunner)
outrunner
In the first case, the rotor rotates inside the stator, and in the second, the rotor rotates around the stator.
Inrunner type motor used in the case when it is necessary to obtain high rotational speed. This motor has a simpler standard design that allows a fixed stator to be used to mount the motor.
Outrunner engine suitable for high torque at low rpm. In this case, the motor is mounted using a fixed axle.
Inrunner type motor- high revs, low torque. Outrunner engine- low revs, high torque.
The number of poles in the DC motor can be different. Some of the characteristics of the motor can be judged by the number of poles. For example, a motor with a 2-pole rotor has a higher speed and lower torque. Motors with an increased number of poles have a higher torque, but a lower number of revolutions. By changing the number of rotor poles, you can change the speed of the engine. Thus, by changing the design of the engine, the manufacturer can select the necessary engine parameters in terms of torque and speed.
Office of the BDPT
Speed regulator, appearance
To control the brushless motor, use special controller - motor shaft speed regulator direct current. Its task is to generate and supply the required voltage to the right winding at the right time. In a controller for devices powered from a 220 V network, an inverter circuit is most often used, in which current is converted at a frequency of 50 Hz, first into direct current, and then into signals with pulse width modulation (PWM). Powerful electronic switches on bipolar transistors or other power elements are used to supply the supply voltage to the stator windings.
The power and speed of the engine is adjusted by changing the duty cycle of the pulses, and, consequently, by the effective value of the voltage supplied to the stator windings of the engine.
Schematic diagram of the speed controller. K1-K6 - keys D1-D3 - rotor position sensors (Hall sensors)
An important issue is the timely connection of electronic keys to each winding. To ensure this the controller must determine the position of the rotor and its speed... To obtain such information, optical or magnetic sensors can be used (for example, Hall sensors), as well as reverse magnetic fields.
More common use Hall sensors, which react to the presence of a magnetic field... The sensors are placed on the stator so that the rotor's magnetic field acts on them. In some cases, the sensors are installed in devices that allow changing the position of the sensors and, accordingly, adjusting the timing.
Rotor speed controllers are very sensitive to the strength of the current passing through it. If you pick up a rechargeable battery with a higher output amperage, the regulator will burn out! Choose the right combination of characteristics!
Advantages and disadvantages
Compared to conventional engines, BDPTs have the following advantages:
- high efficiency;
- high performance;
- the ability to change the speed;
- no sparking brushes;
- low noise, both in the audio and high-frequency ranges;
- reliability;
- ability to withstand torque overload;
- excellent ratio of size and power.
The brushless motor is highly efficient. It can reach 93-95%.
The high reliability of the mechanical part of the detection unit is explained by the fact that it uses ball bearings and does not have brushes. The demagnetization of permanent magnets is rather slow, especially if they are made using rare earth elements. When used in a current protection controller, the service life of this unit is quite long. Actually the service life of the BCD motor can be determined by the service life of the ball bearings.
The disadvantages of BDPT are the complexity of the control system and high cost.
Application
The areas of BDTP application are as follows:
- creating models;
- medicine;
- automotive industry;
- Oil and gas industry;
- Appliances;
- military equipment.
Usage DB for aircraft models gives a significant advantage in terms of power and size. Comparison of the conventional brushed engine of the Speed-400 type and the BDTP of the same class Astro Flight 020 shows that the engine of the first type has an efficiency of 40-60%. The efficiency of the second engine under the same conditions can reach 95%. Thus, the use of the OBD makes it possible to almost double the power of the power section of the model or its flight time.
Due to the low noise and lack of heating during operation, BDPTs are widely used in medicine, especially in dentistry.
In cars, such engines are used in glass lifters, electric wipers, headlight washers and electric seat-lift controls.
Lack of collector and sparking of brushes allows you to use the database as elements of locking devices in the oil and gas industry.
As an example of using the OBD in household appliances, we can mention the LG direct drum washing machine. This company uses an Outrunner type BJTP. There are 12 magnets on the rotor of the motor, and 36 inductors on the stator, which are wound with a wire with a diameter of 1 mm on cores made of magnetic conductive steel. The coils are connected in series, 12 pieces per phase. The resistance of each phase is 12 ohms. A Hall sensor is used as a rotor position sensor. The motor rotor is attached to the washing machine tank.
This engine is widely used in hard drives for computers, which makes them compact, in CD and DVD drives and cooling systems for microelectronic devices and more.
In addition to small and medium-sized DBs, large DBPTs are increasingly used in the heavy-duty industry, the ship and military industries.
Large-capacity OBDs are designed for the US Navy. For example, Powertec has developed a 220 kW BDTP with a speed of 2000 rpm. The engine torque reaches 1080 Nm.
In addition to these areas, DBs are used in the projects of machine tools, presses, lines for the processing of plastics, as well as in wind energy and the use of energy of tidal waves.
Specifications
Main characteristics of the engine:
- rated power;
- maximum power;
- maximum current;
- maximum operating voltage;
- maximum speed(or Kv coefficient);
- winding resistance;
- lead angle;
- operating mode;
- overall weight characteristics engine.
The main indicator of the engine is its rated power, that is, the power generated by the engine for a long time of its operation.
Maximum power- this is the power that the engine can give over a short period of time without collapsing. For example, for the Astro Flight 020 brushless motor mentioned above, it is 250 watts.
Maximum current... For Astro Flight 020 it is 25 A.
Maximum operating voltage- the voltage that the motor windings can withstand. The Astro Flight 020 is set to an operating voltage range of 6 to 12 V.
Maximum engine speed... Sometimes the Kv coefficient is indicated in the passport - the number of engine revolutions per volt. For Astro Flight 020 Kv = 2567 rpm. In this case, the maximum speed can be determined by multiplying this factor by the maximum operating voltage.
Usually winding resistance for motors, it is tenths or thousandths of Ohm. For Astro Flight 020, R = 0.07 ohms. This resistance affects the efficiency of the BDPT.
Lead angle represents the advance of switching the voltages on the windings. It is associated with the inductive nature of the winding resistance.
The operating mode can be long-term or short-term. In long-term operation, the engine can run for a long time. In this case, the heat generated by it is completely dissipated and it does not overheat. In this mode, motors operate, for example, in fans, conveyors or escalators. Short-time mode is used for devices such as an elevator, electric shaver. In these cases, the engine runs for a short time and then cools down for a long time.
The engine passport lists its dimensions and weight. In addition, for example, for engines intended for aircraft models, the landing dimensions and shaft diameter are given. In particular, the following specifications are given for the Astro Flight 020 engine:
- the length is 1.75 ";
- the diameter is 0.98 ";
- the shaft diameter is 1/8 ”;
- weight is 2.5 ounces.
Conclusions:
- In simulation, in various technical products, in industry and in defense technology, BDPTs are used, in which a rotating magnetic field is generated by an electronic circuit.
- By their design, BDPTs can be with an internal (inrunner) and external (outrunner) rotor location.
- Compared to other motors, BDPT have a number of advantages, the main of which are the absence of brushes and arcing, high efficiency and high reliability.
