Powerful brushless DC motors. Brushless motors

A bit of history:

The main problem of all engines is overheating. The rotor rotated inside some kind of stator, and therefore the heat from overheating did not go anywhere. People came up with a brilliant idea: to rotate not the rotor, but the stator, which would be cooled by air during rotation. When such an engine was created, it became widely used in aviation and shipbuilding, and therefore it was nicknamed the Brushless Motor.

Soon an electrical analogue of the brushless motor was created. They called it a brushless motor because it did not have collectors (brushes).

Brushless motor.

Brushless (brushless English) electric motors came to us relatively recently, in recent 10-15 years old. Unlike collector motors they are powered by three-phase alternating current. Brushless motors operate efficiently over a wider RPM range and have more high efficiency . At the same time, the design of the engine is relatively simple, it does not have a brush assembly that constantly rubs against the rotor and creates sparks. We can say that brushless motors practically do not wear out. The cost of brushless motors is slightly higher than brushed motors. This is because all brushless motors have bearings and are generally of higher quality.

Tests have shown:
Rod with screw 8x6 = 754 grams,
RPM = 11550 rpm,
Power consumption = 9 watts(without screw) , 101 watts(with screw),

Power and efficiency

Power can be calculated like this:
1) Power in mechanics is calculated by the following formula: N=F*v, where F is force and v is speed. But since the screw is in a static state, there is no movement, except rotational. If this motor is installed on an aircraft model, then it would be possible to measure the speed (it is equal to 12 m / s) and calculate the useful power:
N useful \u003d 7.54 * 12 \u003d 90.48 watts
2) efficiency electric motor is found according to the following formula: Efficiency = N useful / N spent * 100%, Where N costs = 101 watts
Efficiency= 90.48/101 *100%= 90%
On average, the efficiency of brushless motors is real and fluctuates around 90% (the highest efficiency achieved by this type of motor is 99.68% )

Engine Specifications:

Voltage: 11.1 volts
Turnovers: 11550 rpm
Maximum current: 15A
Power: 200 watts
Thrust: 754 grams (screw 8x6)

Conclusion:

The price of any thing depends on the scale of its production. Manufacturers brushless motors multiply like mushrooms after rain. Therefore, I want to believe that in the near future the price of controllers and brushless engines will fall how it fell on the radio control equipment ... The possibilities of microelectronics are expanding every day, the size and weight of the controllers are gradually decreasing. It can be assumed that in the near future controllers will be built directly into the engines! Maybe we'll live to see this day...

Household and medical appliances, aeromodelling, pipe shut-off drives for gas and oil pipelines - this is far from complete list applications of brushless motors (BD) direct current. Let's look at the device and principle of operation of these electromechanical drives in order to better understand their advantages and disadvantages.

General information, device, scope

One of the reasons for the interest in the DB is the increased need for high-speed micromotors with precise positioning. The internal structure of such drives is shown in Figure 2.

Rice. 2. Imp device commutator motor

As you can see, the design 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 either with an internal anchor (this type of construction can be seen in Figure 2) or external (see Figure 3).

Rice. 3. Design with an external anchor (outrunner)

Accordingly, each of the designs has a specific scope. Devices with an internal armature have high speed rotation, therefore they are used in cooling systems, as power plants drones, etc. Drives with external rotor are used where accurate positioning and resistance to torque overloads are required (robotics, medical equipment, CNC machines, etc.).

Principle of operation

Unlike other drives, for example, asynchronous machine alternating current, for the operation of the DB, a special controller is required, which turns on the windings in such a way that the vectors of the magnetic fields of the armature and the stator are orthogonal to each other. That is, in fact, the driver device regulates the torque acting on the DB armature. This process is clearly shown 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 makes it possible to quickly gain momentum.

Differences between brushed and brushless motors

The collector type drive differs from the DB as design features(see Fig. 5.), and the principle of operation.

Rice. 5. A - collector motor, B - brushless

Consider design differences. Figure 5 shows that the rotor (1 in Fig. 5) of a collector-type motor, unlike a brushless one, has coils in which simple circuit winding, and permanent magnets(usually two) are mounted on the stator (2 in Fig. 5). In addition, a collector is installed on the shaft, to which brushes are connected that supply voltage to the armature windings.

Briefly describe the principle of operation collector machines. When voltage is applied to one of the coils, it is excited and a magnetic field is formed. It interacts with permanent magnets, this causes the armature and the collector placed on it to rotate. As a result, power is supplied to the other winding and the cycle repeats.

The frequency of rotation 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, to increase or decrease the speed, it is enough to increase or decrease the power level. And to reverse it is necessary to switch the polarity. This control method does not require a special controller, since the travel controller can be made based on a variable resistor, and a conventional switch will work as an inverter.

We considered 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 should also be noted that in some drives 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 make this type of drive work, a special 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. You can pick it up by the following characteristics, characteristic of PWM channel drivers:

• The maximum allowable current, this characteristic is given for the normal operation of the device. Quite often, manufacturers indicate this parameter in the model name (for example, Phoenix-18). In some cases, a value is given for peak mode, which the controller can maintain for several seconds.
• The maximum nominal voltage for continuous operation.
• The resistance of the internal circuits of the controller.
• Permissible number of revolutions, indicated in rpm. Above this value, the controller will not allow to increase the rotation (the restriction is implemented at the software level). Please note that the speed is always given for 2-pole drives. If there are more pole pairs, divide the value by their number. For example, the number 60000 rpm is indicated, therefore, for 6 magnetic motor the rotational speed will be 60000/3=20000 prm.
• The frequency of the generated pulses, for most controllers, this parameter lies in the range from 7 to 8 kHz, more expensive models allow you to reprogram the parameter, increasing it to 16 or 32 kHz.

Note that the first three characteristics determine the capacity of the database.

Brushless motor control

As mentioned above, the commutation of the drive windings is controlled electronically. To determine when to switch, the driver monitors the position of the armature using Hall sensors. If the drive is not equipped with such detectors, then the back EMF, which occurs in unconnected stator coils. The controller, which, in fact, is a hardware-software complex, monitors these changes and sets the switching order.

Three-phase brushless DC motor

Most databases are performed in a three-phase design. To control such a drive, the controller has a converter constant voltage into a three-phase pulse (see Fig. 7).

Figure 7. DB voltage diagrams

To explain how such a brushless motor works, one should consider Figure 4 together with Figure 7, where all stages of the drive operation are shown in turn. Let's write them down:

1. 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.
2. Coil "A" is turned off, and a positive pulse goes to "C" ("B" remains unchanged), then a signal is given to the next set of pulses.
3. On "C" - positive, "A" - negative.
4. A pair of "B" and "A" works, which receive positive and negative impulses.
5. A positive pulse is re-applied to "B", and a negative pulse to "C".
6. Coils "A" are turned on (+ is supplied) and a negative pulse is repeated on "C". Then the cycle repeats.

In the apparent simplicity of management there are a lot of difficulties. 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 rotational speed by adjusting the current in the coils. In addition, you should choose the most optimal parameters for acceleration and deceleration. It is also worth noting that the controller must be equipped with a block that allows you to control its operation. Appearance such a multifunctional device can be seen in Figure 8.

Rice. 8. Multi-function brushless motor controller

Advantages and disadvantages

An electric brushless motor has many advantages, namely:

• The service life is much longer than that of conventional collector counterparts.
• High efficiency.
• speed dial top speed rotation.
• 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. Significant disadvantage, which limits the use of the database - 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 short-term activation, for example, to check the performance. Problem repair, especially if rewinding is required.

Published on 19.03.2013

With this article, I begin a series of publications about brushless DC motors. I will describe in accessible language general information, device, control algorithms for a brushless motor. Will be considered different types engines, examples of selection of regulator parameters are given. I will describe the device and the algorithm of the regulator, the method of choosing power switches and the main parameters of the regulator. The logical conclusion of the publications will be the regulator scheme.

Brushless motors have become widespread due to the development of electronics and, in particular, due to the appearance of inexpensive power transistor switches. The appearance of powerful neodymium magnets also played an important role.

However, the brushless motor should not be considered a novelty. The idea of ​​a brushless motor appeared at the dawn of electricity. But, due to the unavailability of technology, it was waiting for its time until 1962, when the first commercial brushless DC motor appeared. Those. For more than half a century, there have been various serial implementations of this type of electric drive!

Some terminology

Brushless DC motors are also called valve motors, in foreign literature BLDCM (BrushLes Direct Current Motor) or PMSM (Permanent Magnet Synchronous Motor).

Structurally, a brushless motor consists of a rotor with permanent magnets and a stator with windings. I draw your attention to the fact that in a collector motor, on the contrary, the windings are on the rotor. Therefore, further in the text, the rotor is magnets, the stator is windings.

An electronic regulator is used to control the engine. In foreign literature Speed ​​Controller or ESC (Electronic speed control).

What is a brushless motor?

Usually people, faced with something new, look for analogies. Sometimes you have to hear the phrase “well, it’s like a synchronizer”, or even worse, “it looks like a stepper”. Since most brushless motors are 3-phase, this is even more confusing, leading to the misconception that the regulator is "feeding" the motor with 3-phase AC current. All of the above is only partly true. The fact is that all motors except asynchronous can be called synchronous. All DC motors are synchronous with self-synchronization, but their principle of operation differs from synchronous AC motors, which do not have self-synchronization. As a stepper brushless motor, it can also probably work. But here is the thing: a brick can also fly ... however, not far, because it is not intended for this. As stepper motor a brushless reluctance motor is more suitable.

Let's try to figure out what a brushless DC motor (Brushles Direct Current Motor) is. In this phrase itself, the answer is already hidden - this is a DC motor without a collector. The functions of the collector are performed by electronics.

Advantages and disadvantages

A rather complex, heavy and sparking assembly, the collector, is removed from the engine design. The design of the engine is greatly simplified. The engine is lighter and more compact. Significantly reduced switching losses as commutator and brush contacts are replaced electronic keys. As a result, we get an electric motor with the best efficiency and power per kilogram. own weight, with the widest range of rotation speed change. In practice, brushless motors heat up less than their collector brothers. endure heavy load by moment. The use of powerful neodymium magnets has made brushless motors even more compact. The design of the brushless motor allows it to be operated in water and aggressive environments (of course, only the motor, the regulator will be very expensive to wet). Brushless motors create virtually no radio interference.

The only drawback is considered complex expensive the electronic unit control (knob or ESC). However, if you want to control engine speed, electronics are indispensable. If you do not need to control the speed of a brushless motor, you still cannot do without an electronic control unit. A brushless motor without electronics is just a piece of iron. There is no way to apply voltage to it and achieve normal rotation like other engines.

What happens in a brushless motor controller?

In order to understand what is happening in the electronics of the regulator that controls the brushless motor, let's go back a little and first understand how the brushless motor works. From the school physics course, we remember how a magnetic field acts on a current-carrying frame. A frame with current rotates in a magnetic field. However, it does not rotate constantly, but rotates to a certain position. In order for continuous rotation to occur, it is necessary to switch the direction of the current in the loop depending on the position of the loop. In our case, the frame with current is the motor winding, and the commutator is engaged in switching - a device with brushes and contacts. The device of the simplest engine, see the figure.

The electronics that control the brushless motor do the same - in right moments connects direct voltage to the desired stator windings.

Encoders, motors without encoders

From the foregoing, it is important to understand that it is necessary to apply voltage to the motor windings depending on the position of the rotor. Therefore, electronics must be able to determine the position of the motor rotor . For this, position sensors are used. They can be various types, optical, magnetic, etc. Currently, discrete sensors based on the Hall effect (for example, SS41) are very common. A 3-phase brushless motor uses 3 sensors. Thanks to such sensors, the electronic control unit always knows what position the rotor is in and which windings to apply voltage at any given time. Later, the control algorithm for a three-phase brushless motor will be considered.

There are brushless motors that do not have sensors. In such motors, the position of the rotor is determined by measuring the voltage on the unused in this moment winding time. These methods will also be discussed later. You should pay attention to an essential point: this method is relevant only when the engine is rotating. When the motor is not turning or is turning very slowly, this method does not work.

In what cases are brushless motors with sensors used, and in what cases without sensors? What is their difference?

Motors with encoders are preferred from a technical point of view. The control algorithm for such engines is much simpler. However, there are also disadvantages: it is required to provide power to the sensors and lay wires from the sensors in the engine to the control electronics; in the event of failure of one of the sensors, the engine stops working, and the replacement of the sensors, as a rule, requires disassembly of the engine.

In cases where it is structurally impossible to place sensors in the motor housing, motors without sensors are used. Structurally, such motors practically do not differ from motors with sensors. But the electronic unit must be able to control the engine without sensors. In this case, the control unit must comply with the characteristics specific model engine.

If the engine must start with a significant load on the motor shaft (electric transport, lifting mechanisms, etc.), motors with sensors are used.
If the motor starts without a load on the shaft (ventilation, air propeller, a centrifugal clutch, etc. is used), motors without sensors can be used. Remember: a motor without encoders must start with no load on the shaft. If this condition is not met, a motor with encoders should be used. In addition, at the moment of starting the engine without sensors, rotational oscillations of the engine axis are possible in different sides. If this is critical for your system, use a motor with sensors.

Three phase

Three-phase brushless motors purchased most widespread. But they can be one, two, three or more phase. The more phases, the smoother the rotation of the magnetic field, but the more complex the motor control system. The 3-phase system is the most optimal in terms of efficiency/complexity ratio, which is why it has become so widespread. Further, only the three-phase circuit will be considered, as the most common. In fact, the phases are the motor windings. Therefore, if you say “three-winding”, I think this will also be correct. Three windings are connected according to the "star" or "triangle" scheme. A three-phase brushless motor has three wires - winding leads, see figure.

Motors with encoders have an additional 5 wires (2 for position encoder power, and 3 encoder signals).

In a three-phase system, voltage is applied to two of the three windings at any given time. Thus, there are 6 options for applying DC voltage to the motor windings, as shown in the figure below.

Characteristics of a DC motor. Like DC motors, brushless motors operate on direct current. VD can be considered as a DC motor, in which the brush-collector assembly is replaced by electronics, which is emphasized by the word “valve”, that is, “ controlled by power keys" (valves). The phase currents of a brushless motor have a sinusoidal shape. As a rule, an autonomous voltage inverter with pulse-width modulation (PWM) is used as a power amplifier.

The valve motor should be distinguished from the brushless DC motor (BDC), which has a trapezoidal distribution of the magnetic field in the gap and is characterized by a rectangular shape of the phase voltages. The BLDT structure is simpler than the VD structure (there is no coordinate converter, instead of PWM, 120- or 180-degree switching is used, the implementation of which is simpler than PWM).

In the Russian-language literature, a motor is called a valve motor if the back-EMF of the controlled synchronous machine is sinusoidal, and contactless motor DC if the back-EMF is trapezoidal.

In the English-language literature, such motors are usually not considered separately from the electric drive and are referred to under the abbreviations PMSM (Permanent Magnet Synchronous Motor) or BLDC (Brushless Direct Current Motor). It is worth noting that the abbreviation PMSM in English literature is more often used to refer to the synchronous machines themselves with permanent magnets and with a sinusoidal form of phase back-EMF, while the abbreviation BLDC is similar to the Russian abbreviation BDPT and refers to motors with a trapezoidal form of back-EMF (if other form is not specified).

Generally speaking, a brushless motor is not an electric machine in the traditional sense, since its problems affect a number of issues related to the theory of electric drives and automatic control systems: structural organization, the use of sensors and electronic components, as well as software.

BLDC motors, which combine the reliability of AC machines with the good controllability of DC machines, are an alternative to DC motors, which are characterized by a number of shortcomings associated with the control panel, such as sparking, noise, brush wear, poor armature heat dissipation, etc. The absence of the control panel allows use VD in those applications where the use of DPT is difficult or impossible.

Description and principle of operation[ | ]

Rice. 2. The structure of a two-phase brushless motor with a synchronous machine with permanent magnets on the rotor. PC - coordinate converter, PA - power amplifier,
SEMP - synchronous electromechanical converter (synchronous machine), DPR - rotor position sensor.

U α = − u q ⋅ sin ⁡ θ , (\displaystyle u_(\alpha )=-u_(q)\cdot \sin (\theta ),)

U β = (\displaystyle u_(\beta )=) u q ⋅ cos ⁡ θ , (\displaystyle u_(q)\cdot \cos (\theta ),)

where is the angle of rotation of the rotor (and the system of rotating coordinates) relative to the axis α (\displaystyle \alpha ) fixed coordinate system. To measure the instantaneous value of an angle θ (\displaystyle \theta ) a rotor position sensor (RPS) is installed on the HP shaft.

In fact, in this case, it is the assignment of the value of the amplitude of the phase voltages. A PC, carrying out position modulation of the signal u q (\displaystyle u_(q)), generates harmonic signals u α , u β (\displaystyle u_(\alpha ),u_(\beta )), which the power amplifier (PA) converts into phase voltages u A , u B (\displaystyle u_(A),u_(B)). Synchronous motor as part of a brushless motor, it is often called a synchronous electromechanical converter (SEMC).

As a rule, the electronic part of the HP switches the stator phases of the synchronous machine so that the stator magnetic flux vector is orthogonal to the rotor magnetic flux vector (the so-called vector control). If the orthogonality of the stator and rotor flows is observed, the maximum torque of the HP is maintained under conditions of a change in the rotational speed, which prevents the rotor from falling out of synchronism and ensures the operation of the synchronous machine with the highest possible efficiency for it. To determine the current position of the rotor flux, current sensors can be used instead of the rotor position sensor (indirect position measurement).

The electronic part of a modern VD contains a microcontroller and a transistor bridge, and the principle of pulse-width modulation (PWM) is used to form phase currents. The microcontroller monitors compliance with the specified control laws, and also performs system diagnostics and its software protection against emergency situations.

Sometimes there is no rotor position sensor, and the position is estimated by the control system from measurements of current sensors with the help of observers (the so-called "sensorless" control of the HP). In such cases, due to the removal of an expensive and often cumbersome position sensor, the price and weight and dimensions of an electric drive with HP are reduced, but control becomes more complicated, and the accuracy of position and speed determination decreases.

In medium to high power applications, electrical filters can be added to the system to mitigate the negative effects of PWM: winding surges, bearing currents, and reduced efficiency. However, this is true for all types of engines.

Advantages and disadvantages[ | ]

Valve motors are designed to combine best qualities AC motors and DC motors. This determines their dignity.

Advantages:

Valve motors are also characterized by some disadvantages, the main of which is high cost. However, speaking of high cost, one should also take into account the fact that brushless motors are usually used in expensive systems with increased requirements for accuracy and reliability.

Flaws:

Design [ | ]

Structurally, modern valve drives consist of an electromechanical part (synchronous machine and rotor position sensor) and a control part (microcontroller and power bridge).

When referring to the design of the VD, it is useful to keep in mind a non-constructive element of the system - the control program (logic).

The synchronous machine used in the HP consists of a laminated (assembled from separate electrically insulated sheets of electrical steel - to reduce eddy currents) stator, in which a multi-phase (usually two- or three-phase) winding is located, and a rotor (usually on permanent magnets).

Hall sensors are used as rotor position sensors in BDPT, and rotating transformers and accumulating sensors are used in VD. In so-called. In "sensorless" systems, the position information is determined by the control system from the instantaneous values ​​of the phase currents.

Information about the position of the rotor is processed by the microprocessor, which, according to the control program, generates control PWM signals. The low-voltage PWM signals from the microcontroller are then converted by a power amplifier (usually a transistor bridge) into power voltages applied to the motor.

The combination of the rotor position sensor and the electronic assembly in the HP and BDPT can be compared with a certain degree of reliability with the brush-collector unit of the DT. However, remember that motors are rarely used outside the drive. Thus, electronic equipment is characteristic of VD almost to the same extent as for DPT.

stator [ | ]

The stator has a traditional design. It consists of a housing, a core made of electrical steel and a copper winding laid in grooves along the perimeter of the core. The winding is divided into phases, which are laid in grooves in such a way that they are spatially shifted relative to each other by an angle determined by the number of phases. It is known that two phases are sufficient for uniform rotation of the motor shaft of an AC machine. Typically, synchronous machines used in HP are three-phase, but HPs with four- and six-phase windings are also found.

Rotor [ | ]

According to the location of the rotor, brushless motors are divided into intra-rotor (eng. inrunner) and external-rotor (eng. outrunner).

The rotor is made using permanent magnets and usually has two to sixteen pairs of poles with alternating north and south poles.

The emergence of brushless motors is explained by the need to create an electric machine with many advantages. A brushless motor is a device without a collector, the function of which is taken over by the electronics.

BKEPT - brushless DC motors, can be power, for example, 12, 30 volts.

• Selecting the right engine
• Principle of operation
• BKEPT device
• Sensors and their absence
• No sensor
• The concept of PWM frequency
• arduino system
• Engine Mount

Selecting the right engine

To select a unit, it is necessary to compare the principle of operation and features of collector and brushless motors.

From left to right: collector motor and motor FK 28-12 brushless

Collector ones cost less, but develop a low torque rotation speed. They operate on direct current, have a small weight and size, affordable repair for replacement parts. The manifestation of a negative quality is revealed when a huge number of turnovers are received. The brushes contact the commutator, causing friction that can damage the mechanism. The performance of the unit is reduced.

Brushes not only require repair due to rapid wear, but can also lead to overheating of the mechanism.

The main advantage of a brushless DC motor is the lack of torque and switching pins. This means that there are no sources of losses, as in permanent magnet motors. Their functions are performed by MOS transistors. Previously, their cost was high, so they were not available. Today, the price has become acceptable, and the performance has improved significantly. In the absence of a radiator in the system, the power is limited from 2.5 to 4 watts, and the operating current is from 10 to 30 amperes. efficiency brushless motors very tall.

The second advantage is the mechanics settings. The axle is mounted on wide bearings. There are no breaking and erasing elements in the structure.

The only negative is the expensive electronic control unit.

Consider an example of the mechanics of a CNC machine with a spindle.

Replacing the collector motor with a brushless one will protect the CNC spindle from breaking. Under the spindle is meant a shaft with right and left turns of torque. The CNC spindle has big power. The speed of the torque is controlled by the servo tester, and the speed is controlled by the automatic controller. The cost of CNC with a spindle is about 4 thousand rubles.

Principle of operation

The main feature of the mechanism is the absence of a collector. And permanent magnets are installed at the spindle, which is the rotor. Around it are wire windings, which have different magnetic fields. The difference between 12 volt brushless motors is the rotor control sensor located on it. The signals are fed into the speed controller unit.

BKEPT device

The layout of the magnets inside the stator is usually used for two-phase motors with a small number of poles. The principle of torque around the stator is used when it is necessary to obtain a two-phase motor with low speed.

There are four poles on the rotor. Rectangle-shaped magnets are installed by alternating poles. However, the number of poles is not always equal to the number of magnets, which can be 12, 14. But the number of poles must be even. Several magnets can make up one pole.

The picture shows 8 magnets forming 4 poles. The moment of force depends on the power of the magnets.

Sensors and their absence

Travel controllers are divided into two groups: with and without a rotor position sensor.

Current forces are applied to the motor windings at special position rotor. It is determined by electronic system using a position sensor. They are of various types. A popular travel controller is a discrete Hall effect sensor. A three-phase 30 volt motor will use 3 sensors. The electronics unit constantly has data on the position of the rotor and directs the voltage in time to the desired windings.

A common device that changes its conclusions when switching windings.

An open loop device measures current, speed. PWM channels are attached to the bottom of the control system.

Three inputs are connected to the Hall sensor. In the event of a change in the Hall sensor, the process of processing the interrupt begins. To ensure fast response handling of the interrupt, a Hall sensor is connected to the lower pins of the port.

Using a position sensor with a microcontroller

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The cascade strength controller is at the heart of the AVR core, which provides intelligent control of a brushless DC motor. AVR is a chip for performing certain tasks.

The principle of operation of the stroke controller can be with or without a sensor. The AVR board program does:

• starting the engine as quickly as possible without the use of external additional devices;
• speed control by one external potentiometer.

separate view automatic control sma, used in washing machines.

No sensor

To determine the position of the rotor, it is necessary to measure the voltage on the idle winding. This method applicable when the motor is rotating, otherwise it will not work.

Sensorless travel controllers are lighter in weight, which explains their widespread use.

Controllers have the following properties:

• value of maximum direct current;
• the value of the maximum operating voltage;
• number maximum speed;
• resistance of power switches;
• impulse frequency.

When connecting the controller, it is important to keep the wires as short as possible. Due to the occurrence of current surges at the start. If the wire is long, then errors in determining the position of the rotor may occur. Therefore, the controllers are sold with a wire of 12 - 16 cm.

Controllers have many software settings:

• engine shutdown control;
• soft or hard shutdown;
• braking and smooth shutdown;
• advancing power and efficiency;
• soft, hard, quick start;
• current limit;
• gas mode;
• direction change.

The LB11880 controller shown in the figure contains a powerful brushless motor driver, that is, you can run the motor directly to the microcircuit without additional drivers.

The concept of PWM frequency

When the keys are turned on, the full load is applied to the engine. The unit reaches maximum speed. In order to control the motor, you need to provide a power regulator. This is exactly what pulse-width modulation (PWM) does.

The required frequency of opening and closing keys is set. The voltage changes from zero to working. To control the speed, it is necessary to superimpose the PWM signal on the key signals.

The PWM signal can be generated by the device on several outputs. Or create a PWM for a separate key with a program. The circuit becomes simpler. The PWM signal has 4-80 kilohertz.

Increasing the frequency leads to more transition processes, which gives rise to heat. The height of the PWM frequency increases the number of transients, which results in losses on the keys. A small frequency does not give the desired smoothness of control.

To reduce the losses on the keys during transients, PWM signals are applied to the upper or lower switches separately. Direct losses are calculated by the formula P=R*I2, where P is the loss power, R is the switch resistance, I is the current strength.

Less resistance minimizes losses, increases efficiency.

arduino system

Often, a hardware computer is used to control brushless motors. arduino platform. It is based on a board and a development environment in the Wiring language.

The arduino board includes an Atmel AVR microcontroller and element programming and interaction with circuits. The board has a voltage regulator. The Serial Arduino board is a simple inverting circuit for converting signals from one level to another. Programs are installed via USB. Some models, such as the Arduino Mini, require additional fee for programming.

The Arduino programming language uses Standard Processing. Some arduino models allow you to control multiple servers at the same time. Programs are processed by the processor, and compiled by the AVR.

Problems with the controller can occur due to voltage dips and excessive load.

Engine Mount

A motor mount is a mechanism that mounts an engine. Used in engine installations. The motor mount consists of interconnected rods and frame elements. Motor mounts are flat, spatial in terms of elements. Motor mount for a single 30 volt motor or multiple devices. power circuit motor mount consists of a set of rods. The motor mount is installed in a combination of truss and frame elements.

The brushless DC motor is an indispensable unit used both in everyday life and in industry. For example, CNC machine, medical equipment, automotive mechanisms.

BKEPT are distinguished by reliability, high-precision principle of operation, automatic intelligent control and regulation.