Published on 03/19/2013

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

Brushless motors have become widespread thanks to the development of electronics and, in particular, due to the emergence of inexpensive power transistor switches. The emergence 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 dates back to the early days of electricity. But, due to the unavailability of technology, it waited 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!

A bit of terminology

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

Structurally, a brushless motor consists of a permanent magnet rotor 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 the magnets, the stator is the windings.

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

What is a brushless motor?

Usually people, when faced with something new, look for analogies. Sometimes you have to hear the phrases “well, it's like a synchro”, or even worse, “it looks like a step-step”. Since most brushless motors are three-phase, this is further 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 ones, can be called synchronous. All DC motors are self-synchronizing synchronous motors, but their principle of operation is different from AC synchronous motors, which are not self-synchronizing. As a brushless stepper motor, it will probably be able to work too. But here's the thing: a brick, it can also fly ... though not far, because it is not intended for this. A brushless jet motor is more suitable as a stepper motor.

Let's try to figure out what a Brushles Direct Current Motor is. In this very phrase, the answer is already covered - this is a DC motor without a collector. The collector functions 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. Switching losses are significantly reduced, since the collector and brush contacts are replaced by electronic keys. As a result, we get an electric motor with the best efficiency and power per kilogram of its own weight, with the widest range of rotation speed variation. In practice, brushless motors run cooler than their brushed counterparts. They carry a large torque load. 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 generate virtually no radio interference.

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

What happens in a brushless motor governor?

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 commutator motor works. From the school physics course, we remember how a magnetic field acts on a frame with a current. The frame with the current rotates in a magnetic field. Moreover, it does not rotate constantly, but rotates to a certain position. In order for continuous rotation to occur, you need to switch the direction of the current in the frame, depending on the position of the frame. In our case, the frame with the 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 same is done by the electronics that control the brushless motor - at the right moments, it connects a constant voltage to the required stator windings.

Position sensors, motors without sensors

From the above, it is important to understand that voltage must be applied to the motor windings depending on the position of the rotor. Therefore, the electronics must be able to determine the position of the motor rotor. . For this, position sensors are used. They can be of various types, optical, magnetic, etc. Currently, discrete Hall effect sensors (eg SS41) are very common. The 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 to 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 across the unused winding at a given 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 spinning or is spinning very slowly, this method does not work.

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

Motors with encoders are technically more preferable. The control algorithm for such motors is much simpler. However, there are also disadvantages: it is required to provide power to the sensors and wiring from the sensors in the engine to the control electronics; in case of failure of one of the sensors, the engine stops working, and replacing the sensors, as a rule, requires disassembling 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 correspond to the characteristics of a particular engine model.

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

Three phases

Three-phase brushless motors have become the most widespread. But they can be one, two, three or more phase. The more phases, the smoother the rotation of the magnetic field, but also 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 a three-phase scheme will be considered, as the most common. In fact, the phases are the motor windings. Therefore, if you say "three-winding", I think it will also be correct. The three windings are star or delta connected. A three-phase brushless motor has three wires - winding leads, see figure.

Motors with encoders have an additional 5 wires (2-supply of position sensors, and 3 signals from sensors).

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

Modern radio-controlled vehicles, be they aircraft, automobile or marine models, are equipped with powerful, reliable, high-performance electric motors, which can be of different design types. The most common is the brushless system: it is used mainly in cars and aircraft models, since it is for them that the speed and speed play a key role.

BC engine: key features

The main advantages of an engine with this design:

On car models designed for racing on tracks, a brushless drift motor is most often installed: it can withstand high loads and is able to work with the high power required when entering corners at high speeds. The brushless motor can be additionally equipped with a gearbox. Its power depends on the number of turns and the supported current; for aircraft models and racing cars, devices with high performance and power reserve are used.

Where to buy brushless motors for models at the best price?

Here you can find a wide range of brushless motors that are compatible with car and RC aircraft. If you need a BK engine of 1/10 models, then you can buy it from us at an attractive price. All our products are certified and feature high quality, reliable assembly and durability. The motors we offer have robust housings, they are made of the best materials and in compliance with all the intricacies of the design. If you are looking for a reliable brushless motor at an affordable price, this is where you can find what you need. Your model will immediately attract attention and become a real reason for pride, and its technical capabilities will delight all viewers!

Motors in multi-rotor devices are of two types: collector and brushless. Their main difference is that in a collector motor, the windings are on the rotor (rotating part), and in a brushless motor, on the stator. Without going into details, let's say that a brushless motor is preferable to a collector motor because it most satisfies the requirements set for it. Therefore, this article will focus on just this type of motors. You can read more about the difference between brushless and brushed motors in.

Despite the fact that BC motors began to be used relatively recently, the very idea of ​​their device appeared a long time ago. However, the advent of transistor switches and powerful neodymium magnets made their commercial use possible.

BK device - motors

The design of a brushless motor consists of a rotor on which magnets are fixed and a stator on which the windings are located. Just by the relative position of these components, BC engines are divided into inrunner and outrunner.

In multi-rotor systems, the Outrunner scheme is more often used, since it allows the highest torque to be obtained.

Pros and cons of BC - engines

Pros:

• Simplified design of the motor due to the exclusion of the collector from it.
• Higher efficiency.
• Good cooling
• BK engines can run in water! However, do not forget that due to water, rust can form on the mechanical parts of the engine and it will break after some time. To avoid such situations, it is recommended to treat motors with a water-repellent lubricant.
• Lowest RFI

Minuses:

Of the minuses, one can only note the impossibility of using these motors without ESC (speed controllers). This somewhat complicates the design and makes BC motors more expensive than collector motors. However, if the complexity of the design is a priority parameter, then there are BC motors with built-in speed controllers.

How to choose motors for your copter?

When choosing brushless motors, first of all, you should pay attention to the following characteristics:

• Maximum current - this characteristic shows what maximum current the motor winding can withstand in a short period of time. If this time is exceeded, then engine failure is inevitable. This parameter also affects the choice of ESC.
• Maximum voltage - as well as maximum current, shows what voltage can be applied to the winding for a short period of time.
• KV is the number of engine revolutions per volt. Since this indicator directly depends on the load on the motor shaft, it is indicated for the case when there is no load.
• Resistance - the efficiency of the engine depends on the resistance. Therefore, the lower the resistance, the better.

Hello everyone. Today I would like to tell you about the cheapest quadcopter on BC motors with a camera. It will be about a previously unknown model Bayangtoys X16 for me. The closest competitor in terms of price for BC motors is JJRC X1. The review will include the flight of the quadric itself, video from the Foxeer Legend 1 camera and the crash results, in one of which the GitUp Git2 camera was lost.

Specifications

BK motors 2212 / 920KV
Diagonal between motors 35.5cm
8 inch propellers
3S 2200mah battery
Charging time about 3 hours
Flight time up to 16 minutes
Control range up to 350 meters
Frequency 2.4GHz
Equipment for 6 * AA
2MP camera

Bayangtoys X16 came to me along with other parcels, the middleman stuffed it into one big box, and I forgot to check the box “Save the package”. Therefore, I can't say anything about the packaging from the store itself.


The box says that this is an updated version.


Let's move on to the configuration. The instruction is in English, the quality is good. It is written in simple language and everything is intuitive with the help of pictures. I specially photographed this page so that you can see the first jamb: there are flips on the box, but not in the instructions.


We begin to get the contents of the box.


The simplest charger for a 3S battery at 15V and 0.8A with charging via a balancing connector.


I was very pleased with the presence of a human 3S battery at 2200mah. Judging by the date on the battery, it was made quite recently. Weight is 167g. The connection connector is not the most convenient. Most will prefer to re-solder with XT60 or T-plug.






The power supply for the charger comes with a European plug. Produces 15V 0.8A




A complete 2MP camera. Fastening latch. I will put it on the quadcopter, we will fly, but I see no reason to write a video from it. Another point is that it separately costs around $ 13. I'd rather choose a model without it, if such a position was. Then, in terms of price, it would be the leader among the cheapest quadrocopters on BC motors.




To record multimedia, we put a 4GB card and a card reader.


Then I found a package in the box, which contained a lot of things. Let's watch together.


Four legs full of copies of the Syma X8.


They put a Phillips screwdriver for disassembly, and self-tapping screws for attaching the legs. There is also a wrench for tightening the nuts and a hexagon to get the motors.


Two nuts in silver and two in black. Saw a man lost a nut. In order not to buy an additional set, one can be cut into two parts. Black with reverse thread.


The 8-inch propellers left a pleasant impression with their size. There are 8 of them in total.


The equipment operates on 6 * AA. My batteries are lying around in the post office somewhere, so I had to insert ordinary batteries. The compartment cover just snaps into place, there is no fixing with a screw.




Now let's take a closer look at the hardware. There are two black buttons on the top at the end. The left one is responsible for switching costs. There is a Low and High mode. From myself, I note that the low mode is quite dreary, so you should fly at a high one. But the right button does not carry any functional load. At first I thought that they simply forgot to indicate its purpose in the instructions, because flips are indicated on the box! But alas and ah. How much I didn’t press it, how much I didn’t hold, the result was zero.




Above the on / off switch is a lanyard loop around the neck. There are buttons near the sticks, with the help of which we trim the quadcopter, if it is taken away somewhere. When the equipment is turned on, a red LED above the loop lights up.


We move to the bottom of the transmitter. To the left of the screen are fake buttons, to the right is a block of buttons. Central is responsible for returning to the take-off site. There is no GPS in this model, so everything is based on a compass. When the X16 gets close to you, you will have to take over. The down button starts video recording, and the top one is responsible for the photo. The right one turns on Headless mode: regardless of the position of the front and rear, the quadcopter is controlled relative to us.


We pass to the hero of the review himself. The square is white with characteristic red lines on the rays. The red motors look great and the size is great (hello JJRC X1). Distance diagonally from the center of the motors 35.5cm.


Above is a GPS imitation. Disassembly showed that this is a fake. It weighs 5g. Fixed with one screw and looks flimsy. It seems to me that after the first crash it will fall off. There is a black Typhoon lettering on the case.


On the belly there is a 2.5 connector for connecting a camera and a mounting platform. By the way, the camera from Syma X8 fits without any problems.


But there is one point on the downside that is completely incomprehensible to me. The motors are covered with plastic cups. Using the example of other models, I realized that they cover the gears, but here there are BC motors. It is unlikely that they are for cooling motors. What do you think?




The legs are attached with two self-tapping screws. Distance from belly to floor 10.4cm. That is, you can take and install a gimbal and a normal camera.


The battery motor cover is secured with a latch. The battery is kept inside normally, does not dangle. But what I really liked was the presence of plastic posts inside that hold the battery on the sides. If you carefully cut them off, you can insert a battery with a larger capacity.






A fully assembled X16 looks like this.

Disassembly

Knowing the love of many to look at the insides, I disassemble this model without any problems. As said, the GPS antenna is just an imitation. I cannot identify the model of the motors myself due to the lack of any inscriptions, but rcgroups consider 2212 / 920KV. The motor control circuits are located separately on each beam, which is good. You can see the soldering level yourself.

Crash and the lost camera

It was immediately decided to put the complete camera aside and try to attach my favorite GitUp Git2 action camera with the help of available tools. To do this, I installed a fastener on the belly with double-sided tape, a latch into it, and already on it with a screw I fixed a rectangular “frame” fastener. I inserted a camera into the frame. This design did not inspire confidence in me, I thought the fastener with tape would most likely fall off. But I really wanted to shoot a video with stabilization of this camera. By the way, more or less normal suspension. And what do you think? During the flight, the quadrocopter was blown away by a crosswind in the region of 9m / s. Before that, I drove it with my own camera, so I exclude connection breaks right away. I had to scratch about 150 meters across the field, since the grass was 10 centimeters long. When I found it, my joy knew no bounds, and then I immediately fell into a sediment: the camera flew out of the "frame", and the mount was in place. The reflector flew off, there was a crack in the hull, the propeller was bent ... For half an hour I flickered across the field and no result: the camera was lost. They will grind with a combine or find potatoes on sorting.






Frustrated, I went home. I decided not to leave the people without a video of the flight from the side and took the Foxer Legend 1 camera - everything is intuitively clear in it and you can turn the image in the program. This time the camera was secured with reinforced tape and blue tape on top for reliability.


During the flight, everything went fine, until I spoke to my friend and happily blended into the tree branches. It was clearly not my day) Ray - full stuffing, the height of the fall is somewhere on the second or third floor.




Blue insulating tape is our everything) A new case costs around $ 9. With the rest of the spare parts, there are also no problems, props are about $ 3.

I'm not a fan of producing separate videos, so flying, shooting a camera, unpacking and reviewing in one video.

Conclusion

Summing up this model, I can summarize the following.
Weight 526g, battery 167g, with the camera included in the kit, everything weighs 725g. I saw a video of how a liter bottle of water was attached to him. Vomited, of course, but flew. You can safely put a normal gimbal and an action camera. I specially waited a couple of days after the crash and then only began to write a review in order to talk about my impressions less biasedly. When the battery is connected, an audible signal immediately sounds, although the patient himself is turned off. That is, food is already being supplied on board. Therefore, disconnect the battery immediately after landing. Unlocking and locking the motors is extremely simple: move the sticks down to different angles. Fly only on the second costs, because the first ones are completely boring. Flight time with a native camera without shooting and photos was 16 minutes! In the video review, there are moments with the shutdown of the motors. The quadcopter tends to roll over, but by turning on the motors, it quickly returns to its original position. The set comes with a 3S 2200mah battery, which is very cool. Charges in about 3 hours. The quadcopter compartment allows for redevelopment and a larger battery. This is not a racing model, suitable for video enthusiasts. The traction is excellent, the stabilization is normal. I did not fly further than 200 meters, because it is visually bad to observe it already at such a distance. We put fpv and fly further, they promise up to 350 meters. Another plus is ESC separately for each motor. There are already enough spare parts. There is a discrepancy between the box and the instructions for flips: there are none. I will not recommend this quadrocopter for beginners, because there is no propeller protection included in the kit. After crashes, it continues to fly. I haven’t ordered new parts yet, because I don’t know what I want from him. If it were not for the JJRC X1, then it would be the cheapest quad on BK motors. But look at his 8-inch propellers, motors and 3S battery, and now at the X1. The choice towards X16 is obvious.

There will probably be mistakes in the review, so feel free to correct it in the comments. Leave your questions, wishes, clarifications there. And to make it more interesting for everyone to read the following reviews, you can write what interests you from this site in the region of $ 50-100. If I have the opportunity to borrow, then why not? And yes, what are these rudiments under the motors for?

Thank you all for your attention.

The product is provided for writing a review by the store. The review is published in accordance with clause 18 of the Site Rules.

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