For a homemade windmill, it is convenient to use an asynchronous generator. It immediately generates AC, and there is no need to connect an inverter, which simplifies the assembly circuit. This means that all household appliances can be used directly from the windmill. Making an asynchronous generator with your own hands is easy. It is enough to find an old asynchronous motor (HELL) from any household appliance and use it as the basis for a windmill. It will take, however, a simple alteration.
The principle of operation of an induction motor and generator
An induction motor is an AC motor. Its peculiarity is that the magnetic field, which is produced by the current of the stator winding, and the rotor rotate at different frequencies. In synchronous motors, their frequency is the same. The most common IM design includes a phase rotor and a stator, between which there is an air gap. But there are also motors with a squirrel-cage rotor. The active part of the IM is the magnetic circuit and windings. The remaining elements provide structural rigidity, rotation and cooling. The current in such a motor appears due to electromagnetic induction, which occurs when the magnetic field rotates at a certain speed.
In turn, an asynchronous wind generator is an engine that operates in generator mode. The drive wind turbine rotates the rotor and the magnetic field in the same direction. In this case, a negative slip of the rotor occurs, a braking torque appears on the shaft, after which the energy is transferred to the battery. To excite the EMF, the residual magnetization of the rotor comes into play, and the amplification of the EMF occurs due to capacitors.
In order to fit an induction windmill, you need to create a moving magnetic field in it. To do this, carry out a series of transformations:
- Pick up neodymium magnets for the rotor. The strength of the magnetic field depends on their strength and quantity.
- Turn the rotor under the magnets. This can be done with a lathe. Remove a couple of millimeters from the entire surface of the core and additionally make recesses for the magnets. The thickness of the groove depends on the selected magnets.
- Mark the rotor into four poles. Place magnets on each (from eight pieces per pole, but more is better).
- Now you need to fix the magnets. This can be done with superglue, but then hold the elements with your fingers until the glue seizes (on contact with the rotor, the magnets will change their position). Or secure everything with tape.
- The next step is to fill the free space between the magnets with epoxy. To do this, wrap the rotor with magnets with paper, wrap tape over it, and seal the ends of the paper cocoon with plasticine. After making such protection, resin can be poured inside. When the epoxy is completely dry, remove the paper.
- Clean the surface of the rotor with sandpaper. Use medium-grain paper for this.
- Identify two rotor wires that lead to the working winding. Cut off the rest of the wires so as not to get confused.
This completes the basic transformations. Additionally, you can purchase a controller, and make a rectifier for your wind generator from silicon diodes. Also, check motor rotation. If the movement is tight, replace the bearings. Quick tip: if you want to increase the current and also reduce the voltage in your unit, then do not be lazy and rewind the stator with thick wire.
Generator testing
Before installing the finished generator on an axial structure or mast, it must be tested. For testing, you will need a drill or screwdriver, as well as some kind of load, for example, a regular light bulb that you use in everyday life. Connect them to your unit and see at what speed the bulb burns brightly and evenly.
If the testing shows good results, then you can proceed with the installation of the windmill. To do this, it is necessary to manufacture bladed elements, an axial structure, and select a battery. You can read more about how to assemble a wind generator.
Rules for the operation of an asynchronous wind generator
Such a windmill has a number of features that must be considered during operation:
- Be prepared that the efficiency of the finished device will fluctuate constantly (within 50%). It is impossible to eliminate this shortcoming, these are the costs of the energy conversion process.
- Take care of high-quality insulation, as well as grounding the wind generator. This is a mandatory security requirement.
- Make buttons to control the device. This will greatly simplify its use in the future.
- In addition, provide places for connecting measuring devices. This will provide you with data on the operation of your unit, allowing you to carry out diagnostics.
If we compare asynchronous and synchronous wind turbines, then asynchronous ones have both advantages and disadvantages.
The benefits are as follows:
- Powerful devices with a simple design, small size and weight.
- High level of efficiency in power generation.
- There is no need for an inverter, because such a wind generator produces alternating current (220/380V). It can directly power household appliances or operate in parallel with a centralized power supply network.
- The output voltage is very stable.
- The output frequency is independent of the rotor speeds.
- It is highly resistant to short circuits, protected from moisture and dirt.
- It can serve for many years, as it contains few wear parts.
- Operates on capacitor excitation.
The disadvantages are:
- In the absence of a battery, the asynchronous generator may die out at times of overload. This is a limiter for the use of such an aggregate. But for a windmill, such a disadvantage is irrelevant, because its design involves an energy storage device. You can read about how to choose a battery for a windmill.
- Capacitor batteries are expensive, so reworking an old IM is the best solution.
- The turnover of the generator is inversely related to its mass.
Thus, a do-it-yourself wind generator from an asynchronous three-phase motor is an inexpensive and convenient solution for the home.
An asynchronous type wind generator is a great way to extract energy from a frequent companion of weather conditions - the wind. Such a device can not only be purchased, but also made by hand. What are the advantages of an asynchronous motor and how to build it? This will be discussed in this article.
Advantages
The asynchronous generator has a number of advantages.
- There are no electric brushes that wear out quickly, and no rotating windings, which indicates the simplicity of the equipment. Also, an additional source of winding excitation voltage is not needed, which distinguishes this type of device from a synchronous generator.
- Even with high power, the wind generator will not have large dimensions and weight. The same property extends to a price that is affordable to many people.
- The output frequency is in the range from 46 to 60 Hz, which practically does not depend on the speed at which the generator rotor rotates.
DIY wind generator
Converting an induction motor as a generator is quite simple, so this way of acquiring energy is quite common. This modification includes the following:
- rotor groove for magnets;
- gluing the magnet to the rotor;
- pouring magnets with epoxy paint so that they do not fly off;
- rewinding the stator with thick wire to raise the current and reduce the high voltage, although this is not always done.
Before sticking the magnets, the rotor can be marked with four poles, after which the magnets can be placed with a bevel. Each pole of the magnet alternates. Such magnetic poles are made at intervals. After the magnets are located on the rotor, they need to be wrapped with tape and filled with epoxy.
However, when assembling the device, sticking of the rotor may be felt. To fix this, you need to redo the rotor. This process involves knocking the magnets together with the resin, after which they need to be reinstalled, but now this needs to be done more evenly throughout the rotor. After refilling, sticking should decrease. This will also affect the voltage during rotation, which will drop a little, as well as the current, which will rise.
After assembly, the generator can be twisted with a drill and connected to something as a load. To do this, you can connect a lamp for a certain number of watts and watch how it burns, in full heat or not. In addition, you can connect a boiler and observe when and to what extent the water heats up. If all of these tests pass, the induction motor is good to go, but there is more to be done.
The turn came to the assembly of the screw. Blades can be cut from PVC. Then you need to weld a stand for the generator, which has a rotary axis for attaching the tail and the generator itself. You should also assemble a controller for a wind generator and connect the battery for charging.
To reduce the resistance of the generator, it is better to rewind the stator with a thick wire. The higher the winding resistance, the lower the current strength and the higher the voltage.
The efficiency, reliability and simplicity of wind turbines on an asynchronous motor cannot leave indifferent a person who wants to use wind energy as correctly as possible. It is especially attractive that you can make such a design yourself, so that its work will attract even more.
Electricity is an expensive resource, and its environmental safety is in doubt, because. hydrocarbons are used to generate electricity. This depletes the subsoil and poisons the environment. It turns out that you can provide the house with wind energy. Agree, it would be nice to have a backup source of electricity, especially in areas where power outages are common.
The conversion plants are too expensive, but with some effort you can assemble them yourself. Let's try to figure out how to assemble a wind generator with your own hands from a washing machine.
Next, we will tell you what materials and tools will be required for the job. In the article you will find diagrams of a wind generator device from a washing machine, expert advice on assembly and operation, as well as videos that clearly demonstrate the assembly of the device.
Wind turbines are rarely used as the main sources of electricity, but as an additional or alternative they are ideal.
This is a good solution for cottages, private houses located in areas where there are often problems with electricity.
Assembling a windmill from old household appliances and scrap metal is a real action to protect the planet. Garbage is just as urgent an environmental problem as environmental pollution by products of combustion of hydrocarbons.
A homemade wind generator from a screwdriver or a washing machine engine will literally cost a penny, but it will help save decent amounts on energy bills.
This is a good option for zealous hosts who do not want to overpay and are willing to make some efforts to reduce costs.
Often, car generators are used to make windmills with their own hands. They do not look as attractive as industrial production structures, but they are quite functional and cover part of the electricity needs.
A standard wind generator consists of several mechanical devices, the function of which is to convert wind kinetic energy into mechanical energy, and then into electrical energy. We recommend that you look at the article about and its principle of operation.
For the most part, modern models are equipped with three blades to increase efficiency and start working when the wind speed reaches at least 2-3 m / s.
Wind speed is a fundamentally important indicator on which the power of the installation directly depends.
The technical documentation for industrial wind turbines always indicates the nominal wind speed parameters at which the installation operates with maximum efficiency. Most often, this figure is 9-10 m / s.
What energy costs can the installation cover?
Installing a wind turbine is cost-effective if the wind speed reaches 4 m/s.
In this case, almost all needs can be met:
- A device with a power of 0.15-0.2 kW will allow you to switch room lighting to eco-energy. You can also connect a computer or TV.
- A wind turbine with a capacity of 1-5 kW is enough to ensure the operation of basic household appliances, including a refrigerator and a washing machine.
- For autonomous operation of all devices and systems, including heating, you need a 20 kW wind generator.
When designing and assembling a windmill from a washing machine engine, wind speed instability must be taken into account. Electricity can disappear at any second, so the equipment cannot be connected directly to the generator.
The question of wind power generators in our time is very relevant. Many European manufacturers offer wind generators of various capacities, but they are not cheap. And the whole system, including a wind power generator, a DC-to-AC inverter and batteries, is a very expensive pleasure that is unlikely to pay for itself in the near future of use. Such wind turbines cannot be afforded by an ordinary consumer of electrical energy.
From all of the above, we can conclude that the most acute issue is to reduce the cost of obtaining electricity from the wind.
When using permanent magnet generators, you can get a not very high voltage, as a rule, it does not exceed 10 V. And besides, the wind speed is not a constant value. Installations on such generators must always be supplied with batteries and an inverter. But based on the fact that the most optimal batteries are 150 A / h batteries, it is unlikely that anyone will want to deal with such an expensive project (for example, the battery of the PT-76 tank weighs 65 kg and is designed for 140 A / h).
Both automobile generators and synchronous motors were used as a generator. But in both versions, the same drawback requires too high engine rotor speeds, and this, in turn, leads to an increase in the gear ratio of the gearbox, and hence the dimensions of the wind wing. You can also add the instability of the frequency of operation and the difficulty of stabilizing the output voltage, and in the case of a synchronous motor, the dimensions and weight are even larger. To stabilize the output voltage, you can use batteries and an inverter, but this will lead to the circuit that is now used by European manufacturers, which will not be discussed here because it is very expensive.
In the course of long searches and experiments, preference was given to a generator based on an asynchronous motor with a squirrel-cage rotor. When using this scheme, many advantages and only one drawback were revealed.
Advantages: small dimensions and weight with a sufficiently large power; no need for excitation voltage; if you use a low-speed motor, then the power of the rotor can be reduced; the output frequency is practically independent of the rotor speed.
Flaw: This generator cannot be overloaded.
The circuit for switching on an asynchronous motor with a squirrel-cage rotor is shown in Figure No. 1. When the motor rotor rotates, the residual magnetic field acts on one of the stator windings. In this case, a small electric current arises, which charges one of the capacitors C1-C3. Due to the fact that the phase of the voltage on the capacitor lags behind, a magnetic field of an already greater magnitude arises on the rotor, which acts on the next winding. Accordingly, the next capacitor will be charged at a higher voltage. This process continues until the generator rotor enters saturation (1 ... 1.15 s). After that, you can turn on the B2 machine and use the energy generated by the generator. Moreover, for normal operation of the engine in the generator mode, the load power should be no more than 80% of the engine used as a generator. The remaining 20% is used to maintain the voltage on the capacitors, i.e. keeping the generator running. If this condition is exceeded, the voltage on the capacitors will disappear, which means that the magnetic field at the armature will disappear, which will lead to the disappearance of voltage at the terminals of the B2 machine. And it happens almost instantly.
This has its drawbacks and its advantages. The disadvantage is that the re-energization is possible only when the cause of the overload is eliminated and the automatic machine B2 is turned off. The generator will sleepily enter the operating mode (after 1 ... 1.5 s). After that, you can turn on B2 and use energy. The advantage is the factor that the generator is almost impossible to burn, since the voltage at its terminals disappears instantly within 0.1 ... 0.5 s. The output voltage has a sinusoidal shape and is fully suitable for further use. The output frequency of the generator is 46…60 Hz, which in most cases is sufficient for home use. Due to the instability of the voltage at the voltage output, it is necessary to install a stabilizer (a description of the circuit and operation is described in an additional article).
The capacity of additional capacitors is indicated in table No. 1, per one kilowatt of the indicated motor power, and for work with a load - an additional capacity per kilowatt of load.
Table #1 The capacitance of the capacitors included in the phases, in microfarads per 1 kW of power.
|
Voltage between phases |
Main capacitance (uF) |
||
|
At idle |
With active load |
With reactive load |
|
For example, there is a 3 kW motor. It is supposed to connect a reactive load (electric motor, welding machine) with a total power of approximately 2 kW to it. At the same time, we want the voltage between the phases to be 380. This means that the capacitance of the capacitor C1 will be (35) + (26) microfarads. Since C1 \u003d C2 \u003d C3, then we need three capacitors with a capacity of 30 microfarads. If there are no capacitors of the required capacitance, then capacitors can be connected in parallel with a smaller capacitance. Capacitors should be paper or paper for a voltage of at least 450 V, and preferably 650 V. It is better to turn on the generator for a voltage between phases of 220 V, and between zero and phase 127 V. This is due to the fact that for normal operation of the generator, phase imbalance should not exceed. With this scheme, it will be possible to unload the generator as much as possible. In addition, it is better to power incandescent lighting lamps and some heating devices with direct current.
The generator must use a low-speed squirrel-cage motor. A 360-720 rpm motor is best, but a 910 rpm motor will work. This is due to the need to rotate the rotor at about twice the speed than indicated in the passport for the engine, and a decrease in the gear ratio of the gearbox.
The wind turbine itself can be made in any scheme convenient for you. The following construction is also proposed here. The principle of operation is shown in Figure 3 and needs no explanation. The wind turbine (Figure No. 4) consists of a wind wing 1, a support 2 and the generator itself 3. The support is rigidly concreted and reinforced with three tension cables 4. The support can be made of wood, concrete, metal. You can use a support that is used to transmit electricity over a distance, or your own. It is better to use a steel cable with a diameter of 10..12 mm as stretch marks. The crutches for which the stretch marks are attached must be well concreted. The frame of the wings of a wind turbine can be made from pipes with a diameter of 1 inch, its drawing is shown in Figure No. 5. Ailerons can be made from a steel bar with a diameter of 6mm. As a leading ox, a thick-walled pipe with a diameter of 2..2.5 inches was used, into the lower end of which a shaft 300 ... 400 mm long was pressed. A groove for the pulley is made at the lower end of the shaft. Bearings are taken spherical with conical clamps brand 2000810 with a corresponding housing.
After assembly, the wing must be balanced. A balanced wing is attached to the support in any convenient way, but, most importantly, that the mount is sufficiently rigid and reliable. It was experimentally found that the best material for wrapping the wing is a polyethylene film with a thickness of 80 ... 120 microns. It is strong enough, light and cheap, it allows you to abandon the brake mechanism, which, by the way, is unacceptable in this case, since the wing will be destroyed in strong winds. It is necessary to cover with plastic wrap in several layers, soldering at the seams, with a soldering iron through a piece of plastic wrap. The soldered seam must be equal and strong.
A gearbox is used to drive the generator shaft. You can use a gearbox of any system, except for a worm gear. As already mentioned, the generator shaft must be rotated at about twice the speed, and the wind turbine shaft rotates at a speed of 500 rpm with a wind speed of 5 m / s, hence the restriction on using the engine as a generator. The best option might be a 360 rpm motor, but a 720 rpm motor can also be used. When using the engine, you can increase the height of the wing by 500 mm. It is not recommended to increase the wing in width, since the rotation frequency decreases, the same should not be reduced, since with an increase in the rotation speed, the power will greatly decrease, and the law of decrease is not linear.
When selecting a gearbox, the following rules should be followed: for the nominal speed of the wind turbine wing, you need to take the value of 500 rpm, which corresponds to a wind speed of 5 m / s, the rotational speed of the motor shaft increases by 2.3, then by simple calculations we get the transmission coefficient. The bracket itself is easy to attach to the support using six studs. With a gear reducer, mounting is much easier. It is not recommended to make the wind turbine shaft too long, as it can simply be twisted. The entire structure must be grounded. Grounding resistance should be no more than 2 ohms. At the foot it is necessary to put a cabinet in which it is necessary to place capacitors C1-C3, automata B1-B2, diodes V1-V6, a voltage stabilizer, a control machine, four batteries and a powerful voltage converter to provide energy during calm. The automatic control provides switching of power supply circuits depending on the load and wind speed. A powerful voltage converter provides battery charging while the generator is idling, as well as power supply from batteries in the absence of wind or a very low voltage on the generator. When there is no voltage and the batteries are discharged, the automatic control unit provides energy from the standard network.
The cable used to connect the generator and the power cabinet must be three-phase with a conductor cross section of no more. The cables used to connect the cabinet to consumers can be the same. The ground bus must have a cross section of at least.
Attention! All installation work must be carried out with the B1 machine turned off and the capacitors C1-C3 discharged.
This section presents home-made wind turbines with generators based on converted asynchronous motors. Wind turbines based on such motors are very popular, since asynchronous motors are widespread and easily remanufactured. The alteration mainly consists in rewinding the stator, although not always, if the engine is multi-band and low-speed, then it can not be rewound. Also, the rotor of such engines is machined and equipped with permanent magnets, as a result, the engine turns into a low-speed generator for a windmill.
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Wind generator based on an asynchronous motor with a wooden propeller
A small description and photos of a self-made vetogenerator based on an asynchronous motor, which is converted to naodymium magnets 
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Wind generators from the motor-wheel
The article contains a short description with a photo of vetogenerators with generators, in which the motor is a wheel. There are different designs according to the type of mounting of the motor wheel 
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Wind generator 1kW from asynchronous motor
A wind generator from an asynchronous motor 1500 watts, 1500 rpm, four-pole, which was converted to permanent magnets, and the stator was rewound to 12 poles. The strong wind protection scheme is classic with the generator axis shifted from the center. The windmill works on night lighting which turns on automatically. 
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Alteration of an asynchronous motor into a generator for a windmill
Building your own generator for a wind generator is, in principle, and in fact, simple and can be easily carried out without significant costs of both effort and money. To do this, it is enough just to convert the rotor to permanent magnets. 
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Wind generator from asynchronous motor
Another interesting photo story about the conversion of an asynchronous motor into a generator for a wind turbine. The motor rotor was machined for magnets, which, as always, were filled with epoxy. The stator was not rewound, so the generator turned out to be high-voltage with high phase resistance. The wind generator itself is made according to the classical scheme with a folding tail, mounted on a nine-meter mast. 
> Photo story about the manufacture of a wind generator, its debugging and installation, preparation, anemometer. Trial and tests. This material was written according to a photo report of a user under the nickname Sergey, found on one of the forums. The first stage, calibration and installation of the anemometer, conversion of an asynchronous motor into a generator
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