Usually a gentle breeze blows, but my mini windmill periodically spins up to very high speeds, the propeller rotates at such a speed that it is practically invisible, although at such speeds you can hear the barely audible rolling of the blades. Now this windmill keeps an old but working battery in working condition so that it does not discharge. The maximum power of the windmill is only up to 100mA, perhaps it can produce more, but we usually have a slight wind blowing, and measured it in a normal breeze.

I saw the design of similar windmills on an overseas website and decided to replicate it, and that’s how this baby was born. I used it as a generator stepper motor from my inkjet printer, which had been out of service for a long time and was collecting dust. Having disassembled it, I unscrewed the motor. Then he looked, turned it, twirled it with his hands, measured how much it gave, it gave very little, but the volts rose above 12, which means it could theoretically charge the battery.

Next, I made a mount for the blades from the transistor. The transistor was drilled along the diameter of the shaft on which the gear attachment melted, generally to its dimensions. I put the transistor on the shaft, dropped some glue and twisted it, making sure that everything was smooth. Then I finally fixed it with epoxy. I spread it a little and filled the hole of the transistor, additionally protecting the motor from bad weather by covering the holes in the motor. Below is a photo of this generator.

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Next, I cut out blades from a piece of PVC pipe with a diameter of 110 mm, and drew a blank on the pipe, which I cut out with a cutting machine. I took the approximate dimensions: the width was 9cm, and the screw span was 48cm. I drilled holes and screwed the screw to the motor-generator using small bolts.

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For the base, I used a piece of 55th PVC pipe, then cut out the tail from plywood, and added a piece from 110th. Mtorchik glued the pipes in. After assembly, the result was a wind power plant like this. I immediately assembled the rectifier. Since this motor did not want to produce a lot of volts at low speeds, I assembled it using a doubling circuit and turned it on in series.

I took HER307 diodes, capacitors - 3300uF

I wrapped the circuit in polyethylene and inserted a rectifier into the pipe, then a motor and tied it with wire through the drilled holes, covering the space with silicone. I also covered all the holes on top with silicone, and drilled one hole at the bottom, just in case, so that if anything happens, the water would drain out and the condensation would evaporate.

The tail was secured through with a bolt, the semicircular tail was inserted and tied with wire, and it held on firmly. I found the center of gravity, drilled (dia. 9mm.) I also drilled dia. 6mm two M10 bolts, through, under the axle. (The M10 bolts here serve as the “bearing” of the axle) I screwed the M10 bolts into the pipe from above and below, lubricated the long M6 bolt with grease and twisted everything together, it turned out quite rigidly. The axle bolt (M6) was screwed to the corner, and it to the stick. I put a silicone plug on top of the M10 bolt, now the axis is not afraid of water. The wind generator is complete.

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I took several blocks for the mast. which he twisted with self-tapping screws, secured to the windmill and lifted onto the rope. I connected it to the battery, it is charging, but it is very weak, it keeps the battery from naturally discharging. Since the wind was spinning, I was satisfied, at least I’ll know which way the wind is blowing. This option - as stated on that site - is a little weekend project, that is, a small project for the weekend, for the pleasure of picking something up, especially since I don’t I spent not a penny... glue doesn't count. So, in theory, it can light a couple of small LEDs, or charge a mobile phone in a couple of days, but most likely the phone will take such a weak current for a bad contact and turn it off, writing bad connection on the display.

In the future, if I have time and desire, I can do it to illuminate the yard, but I’ll just assemble a second one like this and put in a small battery, or several rechargeable batteries. For this, there is one more stepper left, only this one produces 2x20 volts when cranked by hand, but the current is small. And the second one is on the brushes, immediately permanent. By hand 10 volts, short circuit - 0.5 Ampere. And I’ll still be torturing the autogenerator, but I’ll just wait for the magnets.

While riding a bicycle past summer cottages, I saw a working wind generator:

The large blades rotated slowly but surely, the weather vane oriented the device in the direction of the wind.
I wanted to implement a similar design, even if it was not capable of generating power sufficient to supply “serious” consumers, but it still worked and, for example, charged batteries or powered LEDs.

Stepper motors

One of the most effective options for a small homemade wind generator is to use stepper motor(SD) (English) stepping (stepper, step) motor) - in such a motor, the rotation of the shaft consists of small steps. The windings of the stepper motor are combined into phases. When current is supplied to one of the phases, the shaft moves one step.
These engines are low speed and a generator with such an engine can be connected without a gearbox to a wind turbine, Stirling engine or other low-speed power source. When using a conventional (commutator) engine as a generator direct current to achieve the same results would require 10-15 times higher rotation speed.
A feature of the stepper is a fairly high starting moment (even without an electrical load connected to the generator), reaching 40 grams of force per centimeter.
Coefficient useful action generator with stepper motor reaches 40%.

To check the operation of the stepper motor, you can connect, for example, a red LED. By rotating the motor shaft, you can observe the glow of the LED. The polarity of the LED connection does not matter since the motor produces alternating current.

There are enough treasure troves of these powerful engines are five-inch floppy drives, as well as older printers and scanners.

Engine 1

For example, I have a SD from an old 5.25″ floppy drive that was still part of ZX Spectrum- a compatible computer "Byte".
Such a drive contains two windings, from the ends and the middle of which conclusions are made - a total of six wires:

first winding coil 1) - blue (English) blue) and yellow (eng. yellow);
second winding coil 2) - red (English) red) and white (English) white);
brown (English) brown) wires - leads from the midpoints of each winding (eng. center taps).

disassembled stepper motor

On the left you can see the rotor of the engine, on which the “striped” magnetic poles are visible - north and south. To the right you can see the stator winding, consisting of eight coils.
The resistance of half the winding is ~70 ohms.

I used this motor in the original design of my wind turbine.

Engine 2

A less powerful stepper motor at my disposal T1319635 companies Epoch Electronics Corp. from the scanner HP Scanjet 2400 It has five outputs (unipolar motor):


first winding coil 1) - orange (English) orange) and black (English) black);
second winding coil 2) - brown (English) brown) and yellow (eng. yellow);
red (English) red) wire - terminals connected together from the midpoint of each winding (eng. center taps).

The resistance of half the winding is 58 Ohms, which is indicated on the motor housing.

Engine 3

In an improved version of the wind generator, I used a stepper motor Robotron SPA 42/100-558, produced in the GDR and designed for 12 V:

Wind turbine

There are two possible options for the location of the axis of the impeller (turbine) of a wind generator - horizontal and vertical.

Advantage horizontal(most popular) location axis located in the direction of the wind is a more efficient use of wind energy, the disadvantage is the complication of the design.

I chose vertical arrangement axes - VAWT (vertical axis wind turbine), which significantly simplifies the design and does not require orientation downwind . This option is more suitable for mounting on the roof; it is much more effective in conditions of rapid and frequent changes in wind direction.

I used a type of wind turbine called a Savonius wind turbine. Savonius wind turbine). It was invented in 1922 Sigurd Johannes Savonius) from Finland.

Sigurd Johannes Savonius

The operation of the Savonius wind turbine is based on the fact that resistance drag) the oncoming air flow - the wind of the concave surface of the cylinder (blade) is greater than the convex one.

Aerodynamic drag coefficients ( English drag coefficients) $C_D$

two-dimensional bodies:
concave half of the cylinder (1) - 2.30
convex half of the cylinder (2) - 1.20
flat square plate - 1.17
3D bodies:
concave hollow hemisphere (3) - 1.42
convex hollow hemisphere (4) - 0.38
sphere - 0.5
The indicated values ​​are given for Reynolds numbers. Reynolds numbers) in the range $10^4 - 10^6$. The Reynolds number characterizes the behavior of a body in a medium.

Body resistance force to air flow $(F_D) = ((1 \over 2) (C_D) S \rho (v^2) ) $, where $\rho$ is air density, $v$ is air flow speed, $S $ is the cross-sectional area of ​​the body.

Such a wind turbine rotates in the same direction, regardless of the wind direction:

A similar operating principle is used in the cup anemometer. cup anemometer)- a device for measuring wind speed:

Such an anemometer was invented in 1846 by Irish astronomer John Thomas Romney Robinson ( John Thomas Romney Robinson):

Robinson believed that the cups in his four-cup anemometer moved at one-third the speed of the wind. In reality, this value ranges from two to a little more than three.

Currently, three-cup anemometers developed by Canadian meteorologist John Patterson are used to measure wind speed. John Patterson) in 1926:

Generators on commutator engines DC with vertical microturbine sold at eBay for about $5:

Such a turbine contains four blades arranged along two perpendicular axes, with an impeller diameter of 100 mm, a blade height of 60 mm, a chord length of 30 mm and a segment height of 11 mm. The impeller is mounted on the shaft of a commutator DC micromotor with markings JQ24-125H670. Rated voltage The power supply for such a motor is 3 ... 12 V.
The energy generated by such a generator is enough to light a “white” LED.

Savonius wind turbine rotation speed cannot exceed wind speed , but at the same time this design is characterized high torque (English) torque).

The efficiency of a wind turbine can be assessed by comparing the power generated by the wind generator with the power contained in the wind blowing across the turbine:
$P = (1\over 2) \rho S (v^3)$, where $\rho$ is the air density (about 1.225 kg/m 3 at sea level), $S$ is the swept area of ​​the turbine (eng. swept area), $v$ - wind speed.

My wind turbine

Option 1

Initially, my generator impeller used four blades in the form of segments (halves) of cylinders cut from plastic pipes:


Segment sizes -
segment length - 14 cm;
segment height - 2 cm;
segment chord length - 4 cm;

I installed the assembled structure on a fairly high (6 m 70 cm) wooden mast made of timber, attached with self-tapping screws to a metal frame:

Option 2

The disadvantage of the generator was quite high speed wind required to spin the blades. To increase the surface area I used blades cut from plastic bottles:

Segment sizes -
segment length - 18 cm;
segment height - 5 cm;
segment chord length - 7 cm;
the distance from the beginning of the segment to the center of the rotation axis is 3 cm.

Option 3

The problem turned out to be the strength of the blade holders. At first I used perforated aluminum strips from a Soviet children's construction set with a thickness of 1 mm. After several days of operation, strong gusts of wind led to the breaking of the slats (1). After this failure, I decided to cut the blade holders from foil PCB (2) 1.8 mm thick:

The bending strength of PCB perpendicular to the plate is 204 MPa and is comparable to the bending strength of aluminum - 275 MPa. But the elastic modulus of aluminum $E$ (70,000 MPa) is much greater than that of PCB (10,000 MPa), i.e. texolite is much more elastic than aluminum. This, in my opinion, taking into account the greater thickness of the textolite holders, will provide much greater reliability of fastening the wind generator blades.
The wind generator is mounted on a mast:

Trial operation of the new version of the wind generator showed its reliability even in strong gusts of wind.

The disadvantage of the Savonius turbine is low efficiency - only about 15% of wind energy is converted into shaft rotation energy (this is much less than can be achieved with wind turbine Daria(English) Darrieus wind turbine)), using lifting force (eng. lift). This type of wind turbine was invented by the French aircraft designer Georges Darrieux. (Georges Jean Marie Darrieus) - 1931 US Patent No. 1,835,018 .

Georges Darrieux

The disadvantage of the Daria turbine is that it has very poor self-starting (to generate torque from the wind, the turbine must already be spun up).

Conversion of electrical energy generated by a stepper motor

The stepper motor leads can be connected to two bridge rectifiers made from Schottky diodes to reduce the voltage drop across the diodes.
You can use popular Schottky diodes 1N5817 with a maximum reverse voltage of 20 V, 1N5819- 40 V and a maximum direct average rectified current of 1 A. I connected the outputs of the rectifiers in series to increase the output voltage.
You can also use two midpoint rectifiers. Such a rectifier requires half as many diodes, but at the same time the output voltage is halved.
Then the ripple voltage is smoothed out using a capacitive filter - a 1000 µF capacitor at 25 V. To protect against the increased generated voltage, a 25 V zener diode is connected in parallel with the capacitor.


my wind generator diagram


electronic unit of my wind generator

Wind generator application

The voltage generated by a wind generator depends on the magnitude and constancy of the wind speed.

When the wind sways thin tree branches, the voltage reaches 2 ... 3 V.

When the wind sways the thick branches of trees, the voltage reaches 4 ... 5 V (with strong gusts - up to 7 V).

CONNECTING TO JOULE THIEF

The smoothed voltage from the wind generator capacitor can be supplied to - low voltage DC-DC converter

Resistor value R is selected experimentally (depending on the type of transistor) - it is advisable to use a 4.7 kOhm variable resistor and gradually reduce its resistance, achieving stable operation of the converter.
I assembled such a converter based on germanium pnp-transistor GT308V ( VT) and pulse transformer MIT-4V (coil L1- conclusions 2-3, L2- conclusions 5-6):

CHARGE OF IONISTERS (SUPERCAPACITORS)

Ionistor (supercapacitor, English) supercapacitor) is a hybrid of a capacitor and a chemical current source.
Ionistor - nonpolar element, but one of the terminals may be marked with an “arrow” to indicate the polarity of the residual voltage after it is charged at the manufacturer.
For initial research I used an ionistor with a capacity of 0.22 F for a voltage of 5.5 V (diameter 11.5 mm, height 3.5 mm):

I connected it via a diode to the output through a germanium diode D310.

To limit the maximum charging voltage of the ionistor, you can use a zener diode or a chain of LEDs - I use a chain of two red LEDs:

To prevent the discharge of an already charged ionistor through limiting LEDs HL1 And HL2 I added another diode - VD2.

To be continued

A stepper motor is not only a motor that drives various devices (printer, scanner, etc.), but also a good generator! The main advantage of such a generator is that it does not need high speeds. In other words, even if high speed The stepper motor produces quite a lot of energy. That is, a regular bicycle generator requires initial revolutions until the flashlight begins to shine with bright light. This disadvantage disappears when using a stepper motor.

In turn, the stepper motor also has a number of disadvantages. The main one is large magnetic sticking.

Anyway. First we need to find a stepper motor. The rule works here: The larger the engine, the better.

Let's start with the biggest one. I tore it out of the plotter for printing, it's such a big printer. The engine looks quite large.

Before showing you the stabilization and power diagram, I want to show you the method of attaching it to your bike.

Here is another option with a smaller engine.

I think each of you will choose the most suitable option for him when building.

Well, now it’s time to talk about lanterns and power circuits. Naturally, all lights are LED.

The rectification circuit is conventional: a block of rectifying diodes, a pair of capacitors large capacity and voltage stabilizer.

Typically there are 4 wires coming out of the stepper motor corresponding to two coils. Therefore, there are two rectifier blocks in the figure.

A simple, obvious, but brilliant idea came to mind. After all, if you consider that a stepper motor is not only a motor that provides mechanical work completely different devices (from printers, scanners and other office equipment, to various units used in more serious devices). A stepper motor can also serve as an excellent electricity generator!

And its main advantage in everything is that it does not require high speeds at all; it can work properly even at low loads. That is, even with minimal force directed at it, the stepper motor produces excellent energy. The most important thing is that this energy is quite enough for various needs, such as lighting the road for a cyclist using a flashlight connected to a stepper motor.

Unfortunately, with a conventional generator, a standard bike will still need some initial revs before the flashlight starts emitting beams of light bright enough to clearly illuminate the path. But when using a stepper motor, this drawback is removed by itself, that is, the lighting will be supplied as soon as the wheel begins to rotate.

But it’s true that this miracle of design will still have a number of shortcomings. For example, the most obvious of them is a large magnetic sticking. But in reality it is not so scary for a cyclist.

That when starting work we will need to find some details:
1) The actual stepper motor itself.
2) a couple of high-capacity capacitors.
3) LED lights
4) voltage stabilizer 5-6 volts.

Finding a stepper motor is quite easy due to the fact that it is quite common in all office equipment. The only thing you need to understand is that the larger the stepper motor, the better it is for us.

Here several models of stepper motors and various options for attaching them to the iron horse will be described and presented.
To begin with, let's take the most big engine, which the author managed to obtain. He dismantled it from a regular office plotter for printing (essentially a printer, only several times larger in size).

Externally, the engine is quite large.

But before you start studying the stabilization circuit and the power supply circuit, you should pay attention to the method of attaching this unit to the bike.

If you look at the figure, you will understand that the generator is located closer to the wheel axis and the rotation is transmitted from an additional circle.

And yet, since everyone has their own bicycle model and someone does not want to damage the frame with self-tapping screws, you will need to develop the mount yourself, as well as the circle of rotation; there are really a lot of options here.

If you have no idea how to screw a large stepper motor to a structure, there is a smaller option:

All you have to do is choose a generator option that fits the size of your vehicle.

Well, now that we have dealt with the stepper motors, we can move on to the lights and power circuits.

LED lights must be used. The rectification circuit will look like this: a block of rectifying diodes, several high-capacity capacitors and, of course, a voltage stabilizer. In principle, this is a standard power supply scheme.

The standard stepper motor has four output wires that correspond to two coils. It is for this reason that there are also two rectifier blocks in the image. This homemade generator electricity can easily produce up to 50 volts of voltage at high speeds, so it is better to take appropriate capacitors (voltage above 50). Well, a stabilizer for a voltage of 5-6 volts.

So what is the essence of homemade products, and why was it needed?

It’s all about its advantage, even just starting off, your path will already be brightly illuminated by a flashlight powered by our stepper motor, also known as a generator.

I would also like to note that while moving, the light will not blink or go out - the lighting will be smooth and even.

A stepper motor (SM) for a printer is suitable as a generator for a windmill. Even at a low rotation speed, it produces about 3 watts of power. The voltage can rise above 12 V, which makes it possible to charge a small battery.

Principles of use

Wind turbulence in the surface layers, characteristic of the Russian climate, leads to constant changes in its direction and intensity. Wind generators large sizes, the power of which exceeds 1 kW will be inertial. As a result, they will not have time to fully unwind when the wind direction changes. This is also hampered by the moment of inertia in the plane of rotation. When a side wind acts on an operating wind turbine, it experiences enormous loads, which can lead to its rapid failure.

It is advisable to use a low-power wind generator, made by yourself, which has insignificant inertia. They can be used to charge low-power batteries mobile phones or use LEDs to illuminate your dacha.

In the future, it is better to focus on consumers that do not require conversion of the generated energy, for example, for heating water. A few tens of watts of energy may well be enough to maintain temperature hot water or for additional heating of the heating system so that it does not freeze in winter.

Electrical part

As a generator, you can install a stepper motor (SM) for a printer in a windmill.

Even at a low rotation speed, it produces about 3 watts of power. The voltage can rise above 12 V, which makes it possible to charge a small battery. Other generators operate effectively at a rotation speed of more than 1000 rpm, but they will not be suitable since the windmill rotates at a speed of 200-300 rpm. A gearbox is needed here, but it creates additional resistance and also has a high cost.

In generator mode, the stepper motor produces alternating current, which can be easily converted to direct current using a pair of diode bridges and capacitors. The circuit is easy to assemble with your own hands.

By installing a stabilizer behind the bridges, we obtain a constant output voltage. For visual control, you can also connect an LED. To reduce voltage losses, Schottky diodes are used to rectify it.

In the future, it will be possible to create a wind turbine with a more powerful motor. Such a wind generator will have a high starting torque. The problem can be eliminated by disconnecting the load during startup and at low speeds.

How to make a wind generator

You can make the blades yourself from PVC pipe. The required curvature is selected if you take it with a certain diameter. The blade blank is drawn on the pipe and then cut out with a cutting disc. The propeller span is about 50 cm, and the width of the blades is 10 cm. Afterwards, you should grind the sleeve with a flange to the size of the motor shaft.

It is mounted on the motor shaft and additionally secured with screws, and plastic blades are attached to the flanges. The photo shows two blades, but you can make four by screwing two more similar ones at an angle of 90º. For greater rigidity, a common plate should be installed under the screw heads. It will press the blades closer to the flange.

Plastic products do not last long. Such blades will not withstand prolonged wind with a speed of more than 20 m/s.

The generator is inserted into a piece of pipe to which it is bolted.

A weather vane is attached to the end of the pipe, which is an openwork and lightweight structure made of duralumin. The wind generator is supported on a welded vertical axis, which is inserted into the mast pipe with the possibility of rotation. A thrust bearing or polymer washers can be installed under the flange to reduce friction.

For most designs, the windmill contains a rectifier, which is attached to the moving part. This is not advisable due to the increase in inertia. The electrical board can be placed at the bottom, and the wires from the generator can be brought down to it. Typically there are up to 6 wires coming out of a stepper motor, corresponding to two coils. They require slip rings to transfer electricity from the moving part. It is quite difficult to install brushes on them. The current collection mechanism may be more complex than the wind generator itself. It would also be better to place the windmill so that the generator shaft is vertical. Then the wires will not be tangled around the mast. Such wind generators are more complex, but their inertia is reduced. A bevel gear will be just right here. In this case, you can increase the speed of the generator shaft by selecting the necessary gears with your own hands.

Having secured the windmill at a height of 5-8 m, you can begin to conduct tests and collect data on its capabilities in order to install a more advanced design in the future.

Currently, vertical-axis wind generators are becoming popular.

Some structures even withstand hurricanes well. Combined structures that work in any wind have proven themselves well.

Conclusion

The low-power wind generator operates reliably due to its low inertia. It is easily made at home and is used mainly for recharging small batteries. It can be useful in a country house, at the dacha, or on a camping trip when problems arise with electricity.