Stepper motor bike generator. Low-power wind generator from a stepper motor: a homemade device from a printer Using stepper motors in homemade products

Tigrezno

Below is a guide that will help you "recycle" an old scanner into an impressive generator of electricity.

We will need:

Old scanner;
Rectifier diodes (8 1N4007 diodes were used in the project);
Capacitor 1000uF;
PVC pipe;
Plastic parts (see below);
Aluminum plates (you can use any others).

In addition to the fluorescent tube and electronic components, the scanner has a stepper motor, which is what we need. The photo shows a four-phase stepper motor.

Note 3. Free schema development software http://qucs.sourceforge.net/ was used.

Collecting blades. In details .

Unfortunately, there is no diagram of the device, but it is not so difficult to assemble a similar one from a photograph.

End! Now it remains to wait for a windy day and try out the device, as you can see in the photo - the device generates a stable voltage of 4.95 V. Now you can charge your MP3 player or phone for free!

Here. Great man said. The question is not in the "fabulous efficiency": the energy is still free. The planet will not get poorer from such Kulibins. The question is labor costs and the cost of everything used. The question is very controversial: a vertical line of terrible dimensions, or a horizontal line, but swivel. This is a topic for controversy (or better if someone extinguishes their practical experience and shares it).
Hi everyone. mine is a little more difficult. lighting the yard with LED flashlights (5pcs. 7 LEDs each). the battery costs 7.2 volts 700 mA. assembled according to the voltage doubling scheme. :).
the wind is average, I don’t know how to measure it ... it stopped a little, and it’s not worth the wind.
and here is the head. (removed the multiplier, sticking is much more rural with it, and the difference is minimal, and it doesn’t make noise). My vertical one is generally quiet and has been shining for 1.5 years without a battery (also SD).
mba1 is right, and verticals over 200 rpm are highly doubtful.
It seems to me that the blades are large for such an engine. Adjust the size to the power, you see, it will be a completely correct windmill. Did you change the parameters?
I made the blades narrower and shortened, the diameter was about 1.1m, the speed increased, and it spins when you don’t feel the wind. Phanari already 6:). here is the video - http://depositfiles.com/files/18bs0ha7b
I don’t remember the parameters anymore, with an average wind of about 8 volts, ma-xs, now I don’t really want to climb there, and my head is full of others, I’m waiting for neodymium magnets (24pcs), they will come one of these days :), I’ll make a generator :).
If you need a stepper motor, then not from the scanner, but from the printer, there are two of them in the matrix neck, even during maintenance, with the head moving quickly, the LEDs start to glow. I think to start not with a serious craft, but to start with the engines from the Zhiguli stove, or the motor from the glass cleaner is lying around in the garage.
There are collector engines (for example, DP ..., DPM ...) with a centrifugal speed limiter. Maybe there are ideas how to adapt this for the inverse problem in the generator? It just doesn't seem right to me...
And from ShD3-SHD5 someone can muddle?
Or with motors from aircraft models, small sizes, high power?
http://vkontakte.ru/club11998700 - THERE ARE PHOTOS AND VIDEOS SD, neodymium, links ....
What are the engine settings? volt per coil? amperage? how many coils (pins?) and what degree of rotation?
it is desirable to select shd - less winding resistance, higher operating voltage, then a decent impulse will give a step :)
If there is less resistance at a higher voltage, then the power is greater. So you can choose according to SIZE :)
http://www.youtube.com/watch?v=7WgS4kxobI0&feature=channel_video_title
This is my video.
Who knows, any SD can be used as a generator? If you buy more powerful than in a printer.
It is difficult to use a powerful stepper motor as a generator. The reason is the large moment of starting.

For the operation of almost all electrical appliances, special drive mechanisms are required. We propose to consider what a stepper motor is, its design, principle of operation and connection diagrams.

What is a stepper motor?

A stepper motor is an electrical machine designed to convert the electrical energy of the network into mechanical energy. Structurally, it consists of stator windings and a soft or hard magnetic rotor. A distinctive feature of a stepper motor is discrete rotation, in which a given number of pulses corresponds to a certain number of steps. Such devices are most widely used in CNC machine tools, robotics, information storage and reading devices.

Unlike other types of machines, a stepper motor does not rotate continuously, but in steps, from which the name of the device comes. Each such step is only a part of its full turnover. The number of steps required for a full rotation of the shaft will differ depending on the connection scheme, motor brand and control method.

Advantages and disadvantages of a stepper motor

The benefits of using a stepper motor include:

In stepper motors, the angle of rotation corresponds to the number of electrical signals applied, while, after stopping the rotation, the full torque and fixation are maintained;
Precise positioning - provides 3 - 5% of the set step, which does not accumulate from step to step;
Provides high speed start, reverse, stop;
It is distinguished by high reliability due to the absence of rubbing components for current collection, unlike collector motors;
The stepper motor does not require feedback for positioning;
Can deliver low rpm for directly applied load without any gears;
Relatively lower cost relative to the same;
A wide range of shaft speed control is provided by changing the frequency of electrical impulses.

The disadvantages of using a stepper motor include:

A resonance effect and slippage of the stepper unit may occur;
There is a possibility of losing control due to lack of feedback;
The amount of electricity consumed does not depend on the presence or absence of a load;
Difficulties in control due to the peculiarity of the circuit

Device and principle of operation

Rice. 1. The principle of operation of the stepper motor

Figure 1 shows 4 windings that belong to the motor stator, and their arrangement is arranged so that they are at an angle of 90º relative to each other. From which it follows that such a machine is characterized by a step size of 90º.

At the moment the voltage U1 is applied to the first winding, the rotor moves by the same 90º. In the case of alternately applying voltage U2, U3, U4 to the corresponding windings, the shaft will continue to rotate until the completion of a full circle. Then the cycle repeats again. To change the direction of rotation, it is enough to change the order in which pulses are supplied to the corresponding windings.

Types of stepper motors

To ensure various operating parameters, both the step size by which the shaft will move and the moment applied to move are important. Variations of these parameters are achieved due to the design of the rotor itself, the connection method and the design of the windings.

According to the design of the rotor

The rotating element provides magnetic interaction with the electromagnetic field of the stator. Therefore, its design and technical features directly determine the operating mode and rotation parameters of the stepping unit. In order to determine the type of stepper motor in practice, with a de-energized network, it is necessary to turn the shaft, if you feel resistance, then this indicates the presence of a magnet, otherwise, this is a design without magnetic resistance.

Reactive

A reactive stepper motor is not equipped with a magnet on the rotor, but is made of soft magnetic alloys, as a rule, it is assembled from plates to reduce induction losses. The design in cross section resembles a gear with teeth. The poles of the stator windings are powered by opposite pairs and create a magnetic force to move the rotor, which moves from the alternating flow of electric current in the winding pairs.

A significant advantage of this design of the stepper drive is the absence of a locking moment generated by the field in relation to the armature. In fact, this is the same one in which the rotation of the rotor goes in accordance with the stator field. The disadvantage is the reduction in the amount of torque. The step for a jet engine ranges from 5 to 15 °.

With permanent magnets

In this case, the moving element of the stepper motor is assembled from a permanent magnet, which may have two or more poles. The rotation of the rotor is provided by the attraction or repulsion of the magnetic poles by the electric field when voltage is applied to the corresponding windings. For this design, the angular pitch is 45-90°.

hybrid

It was designed to bring together best qualities two previous models, due to which the unit has a smaller angle and pitch. Its rotor is made in the form of a cylindrical permanent magnet, which is magnetized along the longitudinal axis. Structurally, it looks like two round poles, on the surface of which there are rotor teeth made of soft magnetic material. This solution made it possible to provide excellent holding and torque.

The benefits of a hybrid stepper motor are its high precision, smoothness and speed of movement, in small steps - from 0.9 to 5 °. They are used for high-end CNC machines, computer and office equipment and modern robotics. The only drawback is the relatively high cost.

For example, let's analyze the hybrid stepper motor for 200 shaft positioning steps. Accordingly, each of the cylinders will have 50 teeth, one of them is a positive pole, the second is negative. In this case, each positive tooth is located opposite the groove in the negative cylinder and vice versa. Structurally, it looks like this:

Because of this, 100 alternating poles with excellent polarity are obtained on the stepper motor shaft. The stator also has teeth as shown in Figure 6 below, except for the gaps between its components.

Rice. 6. Working principle of hybrid stepper motor

Due to this design, it is possible to achieve a displacement of the same south pole relative to the stator in 50 different positions. Due to the difference in the position in the half-position between the north and south poles, the possibility of moving in 100 positions is achieved, and the phase shift by a quarter division makes it possible to double the number of steps due to sequential excitation, that is, up to 200 steps of the angular shaft per 1 revolution.

Pay attention to Figure 6, the principle of operation of such a stepper motor is that when current is supplied in pairs to opposite windings, the opposite poles of the rotor located behind the stator teeth are pulled up and the same-named poles are repelled in front of them in the direction of rotation.

By type of windings

In practice, a stepper motor is a polyphase motor. The smoothness of work in which directly depends on the number of windings - the more there are, the smoother the rotation occurs, but also the higher the cost. In this case, the torque does not increase from the number of phases, although for normal operation their minimum number on the motor stator must be at least two. The number of phases does not determine the number of windings, so a two-phase stepper motor can have four or more windings.

Unipolar

A unipolar stepper motor is different in that the winding connection circuit has a branch from the midpoint. This makes it easy to change the magnetic poles. The disadvantage of this design is the use of only one half of the available turns, due to which less torque is achieved. Therefore, they are large in size.

To use the full power of the coil, the middle terminal is left unconnected. Consider the designs of unipolar units, they can contain 5 and 6 pins. Their number will depend on whether the middle wire is output separately from each motor winding or they are connected together.

Bipolar

The bipolar stepper motor is connected to the controller via 4 pins. In this case, the windings can be connected internally both in series and in parallel. Consider an example of his work in the figure.

In the structural diagram of such a motor, you see with one excitation winding in each phase. Because of this, changing the direction of the current requires the use of special drivers in the electronic circuit (electronic chips designed to control). A similar effect can be achieved by turning on the H-bridge. Compared to the previous one, the bipolar device provides the same torque in a much smaller package.

Connecting a stepper motor

To power the windings, you will need a device capable of delivering a control pulse or a series of pulses in a certain sequence. Such blocks are semiconductor devices for connecting a stepper motor, microprocessor drivers. In which there is a set of output terminals, each of them determines the power supply method and operation mode.

Depending on the connection scheme, one or another output of the stepper unit must be used. With various options for summing up certain terminals to the DC output signal, a certain rotational speed, step or microstep of linear movement in the plane is obtained. Since some tasks need a low frequency, while others need a high one, the same motor can set the parameter at the expense of the driver.

Typical stepper motor connection diagrams

Depending on how many conclusions are presented on a particular stepper motor: 4, 6 or 8 pins, it will be different and the possibility of using one or another scheme for their connection Look at the pictures, here are typical options for connecting a stepper mechanism:

Wiring diagrams various types stepper motors

Provided that the main poles of the stepper machine are powered from the same driver, according to these schemes, the following distinctive features of work can be noted:

The outputs are uniquely connected to the corresponding terminals of the device. When the windings are connected in series, it increases the inductance of the windings, but reduces the current.
Provides passport value electrical characteristics. In a parallel circuit, the current increases and the inductance decreases.
When connecting one phase per winding, the torque will decrease by low revs and reduce currents.
When connected, carries out all electrical and dynamic characteristics according to the passport, rated currents. The control scheme is greatly simplified.
Gives out much more torque and is used for high speeds;
Like the previous one, it is designed to increase torque, but is used for low speeds.

Stepper motor control

The operation of a stepping unit can be carried out in several ways. Each of which differs in the way the signals are applied to the pairs of poles. In total, a shooting range of the winding activation method is distinguished.

Wave- in this mode, only one winding is excited, to which the rotor poles are attracted. At the same time, the stepper motor is not capable of pulling a large load, since it produces only half of the torque.

full step- in this mode, simultaneous switching of phases occurs, that is, both are excited at once. Because of this, the maximum torque is provided, in the case of a parallel connection or series connection of the windings, the maximum voltage or current will be created.

half step- is a combination of the two previous methods of switching windings. During the implementation of which, in a stepper motor, voltage is alternately applied first to one coil, and then to two at once. This results in a better fixation on maximum speeds and more steps.

For softer control and overcoming the rotor inertia, microstepping control is used, when the sinusoid of the signal is carried out by microstepping pulses. Due to which the forces of interaction of magnetic circuits in a stepper motor get a smoother change and, as a result, the movement of the rotor between the poles. Allows you to significantly reduce the jerks of the stepper motor.

Without controller

The H-bridge system is used to control brushless motors. Which allows you to switch the polarity to reverse the stepper motor. It can be performed on transistors or microcircuits that create a logical chain for moving keys.

As you can see, from the power supply V, voltage is applied to the bridge. When the contacts S1 - S4 or S3 - S2 are connected in pairs, current will flow through the motor windings. Which will cause rotation in one direction or another.

with controller

The controller device allows you to control the stepper motor in various modes. The controller is based on the electronic unit, which forms groups of signals and their sequence sent to the stator coils. To prevent the possibility of damage in the event of a short circuit or other emergency situation on the motor itself, each output is protected by a diode that does not miss the pulse in the opposite direction.

Connection via unipolar stepper motor controller

Popular stepper motor control schemes

Control circuit from a controller with a differential output

It is one of the most noise-proof ways of working. In this case, the direct and inverse signal is directly connected to the corresponding poles. In such a circuit, shielding of the signal conductor must be applied. Great for low power loads.

Control circuit from a controller with an open collector output

In this circuit, the positive inputs of the controller are combined, which are connected to the positive pole. In the case of power supply above 9V, a special resistor must be included in the circuit to limit the current. Allows you to set the required number of steps with a strictly set speed, determine acceleration, etc.

The simplest do-it-yourself stepper motor driver

To assemble a driver circuit at home, some items from old printers, computers and other equipment may come in handy. You will need transistors, diodes, resistors (R) and an IC (RG).

To build a program, be guided by the following principle: when a logical unit is applied to one of the outputs D (the rest signal zero), the transistor opens and the signal passes to the motor coil. Thus, one step is completed.

Based on the circuit, a printed circuit board is compiled, which you can try to make yourself or make to order. After that, the corresponding parts are soldered on the board. The device is able to control the stepper from a home computer by connecting to a regular USB port.

Useful video

Wind is free energy! So let's use it for personal purposes. If the creation of a wind farm on an industrial scale is very expensive, because in addition to the generator it is necessary to carry out a number of studies and calculations, the state does not bear such expenses, and for some reason investors in the countries of the former USSR are not of particular interest. Then privately you can make a mini-windmill for your own needs. It should be understood that the project of converting your home to alternative energy is a very expensive undertaking.

As already mentioned: you need to make long-term observations and calculations in order to choose the optimal ratio of the sizes of the wind wheel and generator, suitable for your climate, wind rose and average annual wind speed.

The efficiency of a wind power plant within the same region can differ significantly, this is due to the fact that the movement of the wind depends not only on the climatic zone, but also on the terrain.

However, you can find out what wind energy is at a minimal cost by assembling a budget installation to power a low-power load, such as a smartphone, light bulbs or a radio. With the right approach, you can provide electricity to a small house or summer cottage.

Let's look at how you can make the simplest wind turbine with your own hands.

Low-power windmills from improvised means

A computer cooler is a brushless motor, which in its original form is of no practical value.

It needs to be rewound, since in the original the windings are connected in an inappropriate way. Winding coils alternately:

Clockwise;

Counterclock-wise;

Clockwise;

Counterclock-wise.

You need to connect adjacent coils in series, or even better, wind it with one piece of wire, moving from one groove to another. In this case, choose the thickness of the wire arbitrarily, it would be better if you wind as many turns as possible, and this is possible when using the thinnest wire.

The output voltage from such a generator will be variable, and its value will depend on the speed (wind speed), install a diode bridge from Schottky diodes to straighten it to a constant, ordinary diodes will do, but it will be worse, because. voltage will drop from 1 to 2 volts.

Lyrical digression, a little theory

Remember the value of the EMF is:

where L is the length of the conductor placed in a magnetic field; V is the speed of rotation of the magnetic field;

When upgrading the generator, you can only influence the length of the conductor, that is, the number of turns of each of the coils. The number of turns - determines the output voltage, and the thickness of the wire - the maximum current load.

In practice, it is impossible to influence the wind speed. However, there is also a way out of this situation, you can find out typical speed wind turbine for your area, design the appropriate RPM propeller for the wind turbine, as well as a reducer or belt drive, to provide sufficient RPM to generate the required voltage.

IMPORTANT: Faster does not mean better! If the rotation speed of the wind generator is too high, its resource will be reduced, the lubricating properties of the bushings or bearings of the rotor will deteriorate, and it will jam, and the breakdown of the winding insulation in the generator will most likely occur

The generator consists of:

We increase the power of the generator from a computer cooler

First, the more blades and wheel diameter, the better, so take a closer look at 120mm coolers.

Secondly, we have already said that the voltage also depends on the magnetic field, the fact is that high power industrial generators have excitation windings, and low power ones have strong magnets. The magnets in the cooler are extremely weak and do not allow good results from the generator, and the gap between the rotor and the stator is very large - about 1 mm, and this is with already weak magnets.

The solution to this problem is to radically change the design of the generator. Rather, only an impeller is required from the cooler; a motor from a printer or any other household appliance can be used as a generator. The most common are brushed motors with permanent magnet excitation.

As a result, it will look like this.

The power of such a generator is enough to power the LEDs, the radio. It will not be enough to recharge the phone, the phone will display the charging process, but the current will be extremely small, up to 100 amperes, with a wind of 5-10 meters per second.

Stepper motors as a wind generator

A stepper motor is very often found in computer and household appliances, in various players, floppy drives (old 5.25” models are interesting), printers (especially dot matrix), scanners, etc.

These motors without alterations can work as a generator, they are a rotor with permanent magnets, and a stator with windings, a typical connection diagram of a stepper motor in generator mode is shown in the figure.

The circuit has a 5 volt linear stabilizer, type L7805, which will allow you to safely connect Cell phones to such a windmill to charge them.

The photo shows a generator from a stepper motor with installed blades.

The engine in a particular case with 4 output wires, the diagram is accordingly for it. An engine with such dimensions in generator mode produces approximately 2 W in light wind (wind speed about 3 m / s) and 5 m / s in strong (up to 10 m / s).

By the way, here is a similar circuit with a zener diode, instead of L7805. Allows you to charge Li-ion batteries.

Refinement of a homemade windmill

To make the generator work more efficiently, you need to make a guide shank for it and fix it movably on the mast. Then, when the direction of the wind changes, the direction of the wind generator will change. Then the following problem arises - the cable going from the generator to the consumer will twist around the mast. To solve this, you need to provide a moving contact. A ready-made solution is sold on Ebay and Aliexpress.

The bottom three wires are motionless going down, and the upper bundle of wires is movable, a sliding contact or a brush mechanism is installed inside. If you do not have the opportunity to buy, be smart, and, inspired by the decision of the designers of the Zhiguli car, namely the implementation of the movable contact of the signal button on the steering wheel, and do something similar. Or use the contact pad from the electric kettle.

By connecting the connectors, you get a moving contact.

Powerful wind generator from improvised means.

For more power, you can use two options:

1. Generator from a screwdriver (10-50 W);

You only need a motor from a screwdriver, the option is similar to the previous one, you can use fan blades as a screw, this will increase the final power of your installation.

Here is an example of such a project:

Pay attention to how a gear overdrive is implemented here - the wind generator shaft is located in a pipe, at its end there is a gear that transmits rotation to a smaller gear mounted on the motor shaft. An increase in engine speed also occurs in industrial wind turbines. Reducers are used everywhere.

However, in a homemade environment, making a gearbox becomes a big problem. You can remove the gearbox from the power tool, it is needed there to lower high revs on the shaft of the collector motor to the normal speed of the cartridge on the drill, or the grinder disk:

The drill has a planetary gearbox;

An angle gearbox is installed in the angle grinder (it will become useful for the installation of some installations and reduce the load from the tail of the wind turbine);

Gearbox from a hand drill.

This version of a homemade wind generator can already charge 12 V batteries, but a converter is needed to generate the charging current and voltage. This task can be simplified by using a car generator.

The advantage of such a generator is the ability to use it for charging car batteries Basically, that's what it's designed for. Autogenerators have a built-in voltage regulator relay, which eliminates the need to buy additional stabilizers or converters.

However, motorists know that at low idling, approximately 500-1000 rpm, the power of such a generator is small, and it does not provide the proper current to charge the battery. This leads to the need to connect to the wind wheel through a gearbox or belt drive.

You can adjust the number of revolutions at wind speeds normal for your latitudes using the selection gear ratio or with the help of a properly designed wind turbine.

Helpful Hints

Perhaps the most convenient windmill mast design for repetition is shown in the picture. Such a mast is stretched on cables fixed to holders in the ground, which ensures stability.

Important: The height of the mast should be as high as possible, approximately 10 meters. At higher altitudes, the wind is stronger because there are no obstacles for it in the form of ground structures, hills and trees. Never install a wind generator on the roof of your house. Resonant vibrations of fastening structures can cause the destruction of its walls.

Take care of the reliability of the carrier mast, because the design of a windmill based on such a generator is much heavier and is already a rather serious solution that can provide autonomous power supply to a summer house with a minimum set of electrical appliances. Devices that operate on 220 Volts can be powered from a 12-220 V inverter. The most common version of such an inverter is.

It is better to use diesel generators, incl. trucks because they are designed to work at low speeds. Average diesel engine large truck operates in the speed range from 300 to 3500 rpm.

Modern generators give out 12 or 24 volts, and a current of 100 amperes has long become normal. After carrying out simple calculations, you can determine that such a generator will give you a maximum of up to 1 kW of power, and a generator from a Zhiguli (12 V 40-60 A) 350-500 W, which is already a pretty decent figure.

What should be a wind wheel for a homemade wind turbine?

I mentioned in the text that the wind wheel should be large and with a large number of blades, in fact this is not the case. This statement was true for those micro-generators that do not claim to be serious electrical machines, but rather specimens for familiarization and leisure.

In fact, the design, calculation and creation of a wind turbine is a very difficult task. Wind energy will be used more rationally if it is made very accurately and the “aviation” profile is ideally displayed, while it must be installed with a minimum angle to the plane of rotation of the wheel.

The real power of wind wheels with the same diameter and different number of blades is the same, the difference is only in the speed of their rotation. The fewer wings, the more revs per minute, with the same wind and diameter. If you are going to achieve maximum RPM, you must mount the wings as accurately as possible with a minimum angle to the plane of their rotation.

Check out the table from the 1956 book "Homemade Wind Farm" ed. DOSAAF Moscow. It shows the relationship between wheel diameter, power and rpm.

At home, these theoretical calculations are of little use, amateurs make wind wheels from improvised means, they use:

Sheets of metal;

Plastic sewer pipes.

You can assemble a high-speed 2-4-blade wind wheel with your own hands from sewer pipes, in addition to them, you need a hacksaw or any other cutting tool. The use of these pipes is due to their shape, after cutting they have a concave shape, which ensures high responsiveness to air flows.

After trimming, they are fixed with BOLTS on a metal, textolite or plywood blank. If you are going to make it from plywood, it is better to glue and twist several layers of plywood on both sides with screws, then you will be able to achieve rigidity.

Here is an idea for a two-bladed one-piece impeller for a stepper motor generator.

conclusions

You can make a wind power plant ranging from low power - units of watts, to power individual LED lamps, beacons and small equipment, to good power values in units of kilowatts, store energy in a battery, use it in its original form or convert up to 220 volts. The cost of such a project will depend on your needs, perhaps the most expensive element is the mast and batteries, it can be in the range of 300-500 dollars.

For the operation of any electrical device, a special drive mechanism is required. A stepper motor is one such device. Today there is big choice various electric motors, divided by type and by the scheme of the driver controlled by the controller.

What is a stepper motor?

A stepper motor is a synchronous electromechanical device, which transmits the control signal to the mechanical movement of the rotor. Rotation occurs in steps that are fixed in a certain position.

How a stepper motor works

When voltage is applied to the terminals, the brushes of the electric motor start and begin to rotate continuously. engine idle move has a special property, it is the transformation of incoming rectangular pulses into a predetermined position of the applied drive shaft.

The shaft moves under fixed angle with every impulse. If several geared electromagnets are located around the central piece of gear-shaped iron, then devices with such a gearbox are quite effective. The microcontroller energizes the electromagnets. One geared electromagnet, under the influence of energy, attracts the teeth of the gear wheel to its surface, thus the motor shaft makes a turn. When the teeth are aligned with the electromagnet, they move slightly towards the adjacent magnetic piece.

To gear started spinning and leveled off with the previous wheel, the first electromagnet is turned off and the next one is turned on. The whole process is then repeated as many times as necessary. This rotation is called constant pitch. By counting the number of steps at a full revolution of the engine, the speed of its rotation is determined.

Stepper motor models

Stepper motors according to the design of the rotor are divided into three types: reactive, permanent magnet and hybrid.

At present, synchronous reluctance motors are rarely used. They are used when a small moment is needed and the pitch angle is too large. The rotor is made of a soft magnetic material with distinct poles, has a large pitch angle, and in the absence of current there is no fixing moment. This is the simplest and cheap engine. The stator has six poles and three phases, while the rotor has four poles. In this case, the step of the device is 30 degrees. A rotating magnetic field is created by connecting the stator phases in series. The rotor turns at an angle less than the stator angle in one step, this is due to the smaller number of poles.
Permanent magnet motor consists of a permanent magnet rotor and a two-phase stator. Unlike reactive devices, in permanent magnet motors, after the control signal is removed, the rotor is fixed. So, it happens due to large torques. Since the manufacturing process of the rotor is accompanied by great technological difficulties (a large number of poles + permanent magnets), a large angular step of up to 90 degrees is obtained. This is their only drawback. When working with a unipolar control circuit, the windings in the center can be tapped. Windings without a central tap are fed through a bipolar control circuit. Based on this, the stepper motor device is divided into two types according to the type of windings, unipolar and bipolar.

Unipolar. You can change the location of the magnetic poles without changing the direction of the current. It is enough to turn on each phase of the winding separately. The device consists of one winding per phase with a tap located in the center.

Bipolar . Such motors have one winding per phase, no general conclusion, and there are two - per phase. Due to this, bipolar devices have more power than unipolar ones. To change the magnetic polarities of the poles, the direction of the current is changed in the winding.

hybrid engine

In order to reduce the pitch angle, a hybrid stepper motor. In its design, it incorporates the best features of a permanent magnet motor and a reluctance motor. The rotor is presented in the form of a cylindrical magnet magnetized along the longitudinal axis. The stator consists of two or four phases, which are placed between pairs of pronounced poles.

How to start a stepper motor, its control

Connection work and stepper motor control will depend on how you want to run the device and how many wires are on the drive. Stepper motors can have from 4 to 8 wires, so a specific scheme is used to connect them.

With four wires. Each phase winding has two wires. To connect the driver step by step, you need to find paired wires with a continuous connection between them. Such a motor is used only with a bipolar device.
With five wires. The central terminals of the motor are internally combined into a solid cable and brought out to one wire. It is impossible to separate the windings from each other, as many gaps will appear. You can get out of the situation if you establish where the center of the wire is and try to connect it with other conductors. This is the most efficient and safe mode. Then the device is connected and checked for operability.
With six wires. Each winding has several wires and a center tap. A measuring device is used to separate the wire. The motor can be connected to a unipolar or bipolar device. When connecting to a unipolar device, all wires are used. For a bipolar device, one end of the wire and one center tap of each winding.

A controller is required to control the stepper motor. The controller is a circuit that supplies voltage to one of the stator coils. The controller is made on the basis of an integrated circuit of the ULN 2003 type, which includes a set of composite keys. Each key has protective diodes at the output, which allow you to connect inductive loads without requiring additional protection.

How does a stepper motor work?

The device can operate in three modes:

microstep mode. Microstepping devices are the latest developments from some manufacturers and are mainly used in microelectronics or industrial conveyors. A special chip creates such a voltage that the shaft becomes in the position of one hundredth of a step, for example, 20 thousand movements occur per 1 revolution. The driver can generate over 50,000 control voltage cycles per revolution.
half mode. Due to the fact that the vibration level is reduced in half step mode, such devices are often used in industry. After one phase is activated, it freezes in this position until the next one turns on. An intermediate position is obtained and two poles act simultaneously on the tooth. When the first phase is switched off, the rotor moves forward half a step.
Full mode. The control voltage is transmitted in turn to all phases and a full step is obtained (200 movements per 1 revolution).

Stepper Motor Specification

In the field of electrical and mechanical engineering, a stepper motor is considered a complex device that includes many mechanical and electrical possibilities. In practice, the following specifications apply:

Rated current and voltage. The maximum allowable current is specified in the mechanical parameters of the electric motor. The rated current is the main electrical parameter at which the engine can operate for as long as necessary. Rated voltage is rarely indicated, it is calculated according to Ohm's law. It shows the constant maximum voltage on the motor winding when it is in static mode.
Phase resistance. The parameter shows what maximum voltage can be applied to the phase winding.
Phase inductance. How quickly the current in the winding will increase is shown by this parameter. In order for the current to increase faster when switching phases at high frequencies, the voltage has to be done more.
The number of full steps in 1 revolution. The parameter shows how accurate the electric motor is, its smoothness and allowable capacity.
Torque. The mechanical data shows the speed, which depends on the torque. The parameter specifies the maximum rotation time of the electric motor.
holding phase. This phase shows the torque when the device is stopped. Two phases of the device must be supplied with rated current.
Stupor moment. During the absence of supply voltage, it is necessary so that the motor shaft can be rotated.
Rotor energy time. Indicates how fast the engine accelerates. The lower the value, the faster the acceleration.
breakdown voltage. The parameter refers to the electrical safety section and shows the lowest voltage that breaks through the insulation between the case and the windings of the device.

In this article, I will describe the entire cycle of manufacturing a stepper motor driver for experiments. This is not the final version, it is designed to control one electric motor and is only needed for research work, the circuit of the final stepper motor driver will be presented in a separate article.

In order to make a stepper motor controller, it is necessary to understand the principle of operation of the stepper electric machines themselves and how they differ from other types of electric motors. And there are a huge variety of electrical machines: direct current, alternating current. AC motors are divided into synchronous and asynchronous. I will not describe each type of electric motors as it is beyond the scope of this article, I will only say that each type of motor has its own advantages and disadvantages. What is a stepper motor and how to control it?

A stepper motor is a synchronous brushless motor with multiple windings (usually four) in which a current applied to one of the stator windings causes the rotor to lock. Sequential activation of the motor windings causes discrete angular movements (steps) of the rotor. The circuit diagram of a stepper motor gives an idea of its structure.

And this picture shows the truth table and the diagram of the operation of the stepper in full-step mode. There are also other modes of operation of stepper motors (half-step, microstep, etc.)

It turns out that if you repeat this sequence of ABCD signals, you can rotate the rotor of the electric motor in one direction.
And how to rotate the rotor in the other direction? Yes, it's very simple, you need to change the sequence of signals from ABCD to DCBA.
But how to turn the rotor to a specific given angle, for example 30 degrees? Each model of a stepper motor has such a parameter as the number of steps. For steppers that I pulled out of dot matrix printers, this parameter is 200 and 52, i.e. to make a full turn of 360 degrees, some engines need to go 200 steps and others 52. It turns out that to turn the rotor at an angle of 30 degrees, you need to go:
-in the first case 30:(360:200)=16.666... (steps) can be rounded up to 17 steps;
-in the second case 30:(360:52)=4.33... (steps), can be rounded up to 4 steps.
As you can see, there is a fairly large error, we can conclude that the more steps the motor has, the smaller the error. The error can be reduced if you use a half-step or micro-step mode of operation or mechanically - use a reduction gear in this case, the speed of movement suffers.
How to control the rotor speed? It is enough to change the duration of the pulses applied to the inputs ABCD, the longer the pulses along the time axis, the less speed rotor rotation.
I believe this information will be enough to have a theoretical understanding of the operation of stepper motors, all other knowledge can be obtained by experimenting.
And so we turn to circuitry. We figured out how to work with a stepper motor, it remains to connect it to the Arduino and write a control program. Unfortunately, it is impossible to directly connect the motor windings to the outputs of our microcontroller for one simple reason - lack of power. Any electric motor passes a sufficiently large current through its windings, and a load of no more than40 mA (ArduinoMega 2560 parameters) . What to do if there is a need to control a load, for example 10A, and even a voltage of 220V? This problem can be solved if a power supply is integrated between the microcontroller and the stepper motor. wiring diagram, then it will be possible to control at least a three-phase electric motor that opens a multi-ton hatch into the missile shaft :-). In our case, the hatch to the rocket shaft does not need to be opened, we just need to make the stepper motor work, and the stepper motor driver will help us with this. Of course, you can buy ready-made solutions, there are a lot of them on the market, but I will make my own driver. To do this, I will need Mosfet power key FETs, as I said, these transistors are ideal for interfacing the Arduino with any loads.
The figure below shows the electrical circuit diagram stepper motor controller.

As power keys I appliedIRF634B transistors maximum source-drain voltage 250V, drain current 8.1A, this is more than enough for my case.With the circuit more or less figured out, we will draw a printed circuit board. I drew in the built-in Paint editor in Windows, I will say this is not the best idea, next time I will use some specialized and simple PCB editor. Below is a drawing of the finished PCB.

Next, we print this image in mirror image on paper using a laser printer. It is best to make the print brightness as high as possible, and you need to use glossy paper, not ordinary office paper, ordinary glossy magazines will do. We take a sheet and print over the existing image. Next, we apply the resulting picture to a pre-prepared piece of foil fiberglass and iron it thoroughly for 20 minutes. The iron must be heated to the maximum temperature.
How to prepare textolite? Firstly, it must be cut to the size of the printed circuit board image (using metal scissors or a hacksaw), and secondly, sand the edges with fine sandpaper so that no burrs remain. It is also necessary to go over the surface of the foil with sandpaper, remove oxides, the foil will acquire an even reddish tint. Next, the surface treated with sandpaper should be wiped with a cotton swab dipped in solvent (use 646 solvent, it stinks less).
After heating with an iron, the toner from the paper is baked onto the surface of the foil fiberglass in the form of an image of the contact tracks. After this operation, the board with paper must be cooled to room temperature and put in a bath of water for about 30 minutes. During this time, the paper will become sour and it must be carefully rolled up with fingertips from the surface of the textolite. Even black traces in the form of contact tracks will remain on the surface. If you failed to transfer the image from paper and you have flaws, then you should wash off the toner from the surface of the textolite with a solvent and repeat it all over again. I got it right the first time.
After obtaining a high-quality image of the tracks, it is necessary to etch the excess copper, for this we need an etching solution that we will prepare ourselves. Previously, for etching printed circuit boards, I used copper sulfate and ordinary table salt in a ratio of 0.5 liters of hot water to 2 tablespoons with a slide of copper sulfate and table salt. All this was thoroughly mixed in water and the solution is ready. But this time I tried a different recipe, very cheap and affordable.
Recommended method for preparing pickling solution:
In 100 ml of pharmacy 3% hydrogen peroxide, 30 g of citric acid and 2 teaspoons of table salt are dissolved. This solution should be enough to etch an area of 100 cm2. Salt in the preparation of the solution can not be spared. Since it plays the role of a catalyst and is practically not consumed in the etching process.
After preparing the solution, the printed circuit board must be lowered into the container with the solution and observe the etching process, the main thing here is not to overdo it. The solution will eat the copper surface not covered with toner, as soon as this happens, the board must be removed and washed with cold water, then it must be dried and the toner removed from the surface of the tracks with a cotton swab and solvent. If your board has holes for mounting radio components or fasteners, it's time to drill them. I omitted this operation due to the fact that this is just a breadboard stepper motor driver, designed to master new technologies for me.
Let's start paving the tracks. This must be done to facilitate your work when soldering. I used to tin with solder and rosin, but I will say this is the "dirty" way. There is a lot of smoke and slag from rosin on the board, which will need to be washed off with a solvent. I applied another method, tinning with glycerin. Glycerin is sold in pharmacies and costs a penny. The surface of the board must be wiped with a cotton swab dipped in glycerin and the solder should be applied with a soldering iron with precise strokes. The surface of the tracks is covered with a thin layer of solder and remains clean, excess glycerin can be removed with a cotton swab or washed with soap and water. Unfortunately, I do not have a photo of the result obtained after tinning, but the resulting quality is impressive.
Next, you need to solder all the radio components to the board; I used tweezers to solder the SMD components. Glycerin was used as a flux. It turned out very neat.
The result is there. Of course, after manufacturing, the board looked better, in the photo it is already after numerous experiments (this is what it was created for).

So our stepper motor driver is ready! Now we pass to the most interesting to practical experiments. We solder all the wires, connect the power source and write a control program for the Arduino.
The Arduino development environment is rich in various libraries, a special Stepper.h library is provided for working with a stepper motor, which we will use. I will not describe how to use the Arduino development environment and describe the syntax of the programming language, you can see this information on the website http://www.arduino.cc/, there is also a description of all libraries with examples, including the description of Stepper.h.

Program listing:
/*
* Test program for stepper
*/
#include
#define STEPS 200

Stepper stepper(STEPS, 31, 33, 35, 37);

void setup()
{
stepper.setSpeed(50);
}

void loop()
{
stepper step(200);
delay(1000);
}

This control program makes one complete revolution of the stepper motor shaft, after a break of one second, repeats indefinitely. You can experiment with the speed of rotation, the direction of rotation and also the angles of rotation.

Also on topic

Defenders of the poor or cold-blooded killers?

What foods not to eat to lose weight

The True Story of Bonnie and Clyde photo

What not to do during pregnancy

Bonnie and Clyde how their story ended