Do-it-yourself single-phase asynchronous generator. How to make a generator for a windmill from an asynchronous motor with your own hands

The desire to have an electric generator in its use is overshadowed by one nuisance - this is high unit cost. Like it or not, but the most low-power models have a rather exorbitant cost - from 15,000 rubles and more. It is this fact that suggests the idea of ​​creating a generator with his own hands. However, himself the process can be difficult, if:

• no skill in working with tools and diagrams;
• no experience in creating such devices;
• The necessary parts and spare parts are not available.

If all this and a great desire are present, then you can try to build a generator, guided by the assembly instructions and the attached diagram.

It's no secret that a purchased power generator will have a more extended list of features and functions, while a home-made product is capable of failing and failing at the most inopportune moments. Therefore, to buy or do it yourself is a purely individual matter that requires a responsible approach.

How an electric generator works

The principle of operation of the electric generator is based on the physical phenomenon of electromagnetic induction. A conductor passing through an artificially created electromagnetic field creates an impulse that is converted into direct current.

The generator has an engine that is capable of generating electricity by burning a certain type of fuel in its compartments:, or. In turn, the fuel, entering the combustion chamber, during the combustion process produces a gas that rotates the crankshaft. The latter transmits an impulse to the driven shaft, which is already capable of providing a certain amount of energy at the output.

The desire to develop an autonomous source for the production of electricity made it possible to build a generator from a conventional asynchronous motor. The development is reliable and relatively simple.

Types and description of an induction motor

There are two types of motors:

1. squirrel-cage rotor. It includes a stator (fixed element) and a rotor (rotating element) driven by bearings attached to two motor shields. The cores are made of steel, and they are also insulated from each other. An insulated wire is located along the grooves of the stator core, and a rod winding is installed along the grooves of the rotor core or melted aluminum is poured. Special jumper rings play the role of the closing element of the rotor winding. Independent developments transform the mechanical movements of the motor and create alternating voltage electricity. Their advantage is that they do not have a collector-alkaline mechanism, which makes them more reliable and durable.
2. phase rotor- an expensive device that requires specialized service. The composition is the same as that of the short circuit rotor. The only exception is the rotor and stator winding of the core is made of insulated wire, and its ends are connected to rings attached to the shaft. Special brushes pass through them, which combine the wires with an adjusting or starting rheostat. Due to the low level of reliability, it is used only for those industries for which it is intended.

Application area

The device is used in various industries:

1. Like a conventional wind power plant engine.
2. For own independent food of an apartment or house.
3. Like small hydroelectric power stations.
4. As an alternative inverter type of generator (welding).
5. To create an uninterruptible power supply system from alternating current.

Advantages and disadvantages of the generator

The positive qualities of the development include:

1. Simple and fast assembly with the ability to avoid dismantling the motor and rewinding the winding.
2. The ability to carry out the rotation of electric current using a wind or hydro turbine.
3. Application of the device in motor-generator systems to convert a single-phase network (220V) to a three-phase network (380V).
4. The ability to use the development in places where there is no electricity, using an internal combustion engine to spin up.

Minuses:

1. The problem of calculating the capacitance of the condensate that is connected to the windings.
2. It is difficult to reach the maximum power mark that self-development is capable of.

Principle of operation

The generator generates electrical energy provided that the number of revolutions of the rotor is slightly higher than the synchronous speed. The simplest type produces about 1800 rpm, given that its synchronous speed level becomes 1500 rpm.

Its principle of operation is based on the conversion of mechanical energy into electricity. It is possible to make the rotor rotate and produce electricity with the help of a strong torque. AT ideal- constant idling, which is able to maintain the same speed.

All types of motors powered by direct current are called asynchronous. They have the stator magnetic field spinning faster than the rotor field, respectively directing it in the direction of its movement. To change the electric motor to a functioning generator, you will need to increase the speed of the rotor so that it does not follow the magnetic field of the stator, but begins to move in the other direction.

You can get a similar result by connecting the device to the mains, with a large capacity or a whole group of capacitors. They charge and store energy from magnetic fields. The capacitor phase has a charge that is opposite to the current source of the motor, due to which the rotor slows down, and current is generated by the stator winding.

Generator circuit

The scheme is very simple and does not require special knowledge and skills. If you start the development without connecting it to the network, rotation will begin and, after reaching the synchronous frequency, the stator winding will begin to generate electrical energy.

By attaching a special battery of several capacitors (C) to its clamps, you can get a leading capacitive current that will create magnetization. The capacitance of the capacitors must be higher than the critical designation C 0, which depends on the dimensions and characteristics of the generator.

In this situation, the process self launch, and a system with a symmetrical three-phase voltage. The indicator of the generated current directly depends on the capacitance for the capacitors, as well as the characteristics of the machine.

Do it yourself

To convert an electric motor into a workable generator, you will need to use non-polar capacitor banks, so it is better not to use electrolytic capacitors.

In a three-phase motor, you can connect a capacitor according to the following schemes:

• "Star"- makes it possible to carry out generation at a smaller number of revolutions, but with a lower output voltage;
• "Triangle"- comes into operation in large numbers revolutions, respectively, produces more voltage.

You can create your own device from a single-phase motor, but provided that it is equipped with a short circuit rotor. To start the development, you should use a phase-shifting capacitor. A single-phase collector-type motor is not suitable for rework.

Required Tools

Creating your own generator is easy, the main thing is to have all the necessary elements:

1. asynchronous motor.
2. Tachogenerator (a device for measuring current) or a tachometer.
3. Capacitor for capacitors.
4. Capacitor.
5. Tools.

Walkthrough

1. Since it will be necessary to reconfigure the generator in such a way that the rotation speed exceeds the engine speed, it is first necessary to connect the engine to the mains and start it. Then, using a tachometer, determine the speed of its rotation.
2. Having learned the speed, you should add another 10% to the resulting designation. For example, the technical indicator of the motor is 1000 rpm, then the generator should have about 1100 rpm (1000*0.1%=100, 1000+100=1100 rpm).
3. It is necessary to choose a capacitance for capacitors. Please refer to the table for sizing.

Table of capacitor capacities

Important! If the capacity is large, the generator will start to heat up.

Choose appropriate capacitors that can provide the required rotation speed. Be careful when installing.

Important! All capacitors must be insulated with a special coating.

The device is ready and can be used as a source of electricity.

Important! A device with a squirrel-cage rotor creates a high voltage, so if you need an indicator of 220V, you should additionally install a step-down transformer.

Magnetic generator

The magnetic generator has several differences. For example, it does not need to install capacitor banks. The magnetic field that will create electricity in the stator winding is created by neodymium magnets.

Features of creating a generator:

1. It is necessary to unscrew both engine covers.
2. You need to remove the rotor.
3. The rotor must be machined by removing upper layer desired thickness (magnet thickness + 2mm). It is extremely difficult to perform this procedure on your own without turning equipment, so you should contact a turning service.
4. Make a template for round magnets on a sheet of paper, based on the parameters, the diameter is 10-20 mm, the thickness is about 10 mm, and the swearing force is about 5-9 kg per cm 2. The size should be selected depending on the dimensions of the rotor. Then attach the created template to the rotor and place the magnets with the poles and at an angle of 15-20 0 to the rotor axis. The approximate number of magnets in one strip is about 8 pieces.
5. You should have 4 groups of stripes, each with 5 stripes. Between groups, a distance of 2 magnet diameters should be maintained, and between strips in a group - 0.5-1 magnet diameter. Due to this arrangement, the rotor will not stick to the stator.
6. Having installed all the magnets, you should fill the rotor with a special epoxy resin. Once dry, cover the cylindrical element with fiberglass and re-impregnate with resin. Such a mount will prevent the magnets from flying out during movement. Make sure that the diameter of the rotor is the same as before the groove, so that during installation it does not rub against the stator winding.
7. After drying the rotor, it can be installed into place and screw both engine covers.
8. Conduct tests. To start the generator, you will need to turn the rotor with an electric drill, and at the output measure the received current with a tachometer.

Remodel or not

To determine whether the operation of a self-made generator is effective, one should calculate how justified the efforts to convert the device are.

It cannot be said that the device is very simple. The motor of an asynchronous motor is not inferior in complexity to a synchronous generator. The only difference is the absence of an electrical circuit to excite the work, but it is replaced by a capacitor bank, which does not simplify the device in any way.

The advantage of capacitors is that they do not require additional maintenance, and energy is obtained from magnetic field rotor or produced electric current. From this we can say that the only plus from this development is the lack of need for maintenance.

Another positive quality- clear factor effect. It consists in the absence of higher harmonics in the generated current, that is, the lower its indicator, the less energy is spent on heating, a magnetic field and other moments. For a three-phase electric motor, this figure is about 2%, while for synchronous machines it is at least 15%. Unfortunately, taking into account the indicator in everyday life, when various types of electrical appliances are connected to the network, is unrealistic.

Other development indicators and properties are negative. It is not capable of providing the rated industrial frequency of the voltage produced. Therefore, the devices are used together with straightening machines, as well as for charging the battery.

The generator is sensitive to the slightest drops in electricity. In industrial applications, a battery is used for excitation, and in homemade version part of the energy goes to the capacitor bank. In the event that the load on the generator is higher than the nominal value, it does not have enough electricity to recharge, and it stops. In some cases, capacitive batteries are used, which change their dynamic volume depending on the load.

1. The device is very dangerous, therefore it is not recommended to use a voltage of 380 V unless absolutely necessary.
2. According to precautions and safety regulations additional grounding is required.
3. Watch the thermal regime of development. It is not inherent to it to work at idle. To reduce the thermal effect, it is necessary to choose a capacitor capacitance well.
4. Correctly calculate the power of the produced electrical voltage. For example, when only one phase functions in a three-phase generator, then the power is 1/3 of the total, and if two phases work, respectively, 2/3.
5. It is possible to indirectly control the frequency of the intermittent current. When the device is idling, the output voltage begins to increase, and exceeds the industrial (220 / 380V) by 4-6%.
6. It's best to isolate development.
7. It is necessary to equip a home-made invention with a tachometer and a voltmeter to capture its work.
8. It is desirable to provide special buttons to turn the mechanism on and off.
9. The level of efficiency will decrease by 30-50%, this phenomenon is inevitable.

All electrical machines operate in accordance with the law of electromagnetic induction, as well as with the law of interaction of a conductor with current and a magnetic field.

Electric machines according to the type of power supply are divided into DC and AC machines. Direct current is generated by uninterruptible power supplies. DC machines are characterized by the property of reversibility. This means that they are capable of operating in both motor and generator modes. This circumstance can be explained in terms of similar phenomena in the operation of both machines. In more detail design features engine and generator are discussed below.

Engine

Engine designed for conversion of electrical energy into mechanical. AT industrial production motors are used as drives on machine tools and other mechanisms that are part of technological processes. Also, motors are used in household appliances, for example, in a washing machine.

When a conductor in the form of a closed frame is in a magnetic field, the forces that are applied to the frame will cause this conductor to rotate. In that case, it will be about the simplest engine.

As mentioned earlier, the operation of a DC motor is carried out from uninterruptible power supplies, for example, from battery, power supply. The motor has an excitation winding. Depending on its connection, motors are distinguished with independent and self-excitation, which, in turn, can be series, parallel and mixed.

AC motor connection is made from electrical network . Based on the principle of operation, motors are divided into synchronous and asynchronous.

The main difference between a synchronous motor is the presence of a winding on a rotating rotor, as well as the existing brush mechanism, which serves to supply current to the windings. The rotation of the rotor is carried out synchronously with the rotation of the magnetic field of the stator. Hence the name of the engine.

In an asynchronous motor important condition is that the rotation of the rotor must be slower than the rotation of the magnetic field. In case of non-compliance this requirement guidance of the electromotive force and the occurrence of electric current in the rotor is impossible.

Asynchronous motors are used more often, but they have one significant drawback - without changing the current frequency, it is impossible to control the speed of rotation of the shaft. This condition does not allow to achieve rotation with a constant frequency. Also a significant disadvantage is the limitation on the maximum rotation speed ( 3000 rpm.).

In cases where it is necessary to achieve a constant shaft rotation speed, the possibility of its regulation, as well as achieving a rotation speed exceeding the maximum possible for asynchronous motors, synchronous motors are used.

Generator

The conductor, moving between two magnetic poles, contributes to the emergence of an electromotive force. When the conductor is closed, then under the influence of an electromotive force, a current appears in it. This phenomenon is based on electric generator.

The generator is capable of producing electrical energy from thermal or chemical energy. However, the most widespread are generators that convert mechanical energy into electrical energy.

Main constituent elements DC generator:

• An anchor acting as a rotor.
• The stator on which the excitation coil is located.
• Frame.
• magnetic poles.
• Collector assembly and brushes.

DC generators are not used as often. The main areas of their application: electric transport, welding inverters as well as wind turbines.

The alternator has a similar design to the DC generator, but differs in the structure of the collector assembly and the windings on the rotor.

As with motors, generators can be either synchronous or asynchronous. The difference between these generators lies in the structure of the rotor. A synchronous generator has inductors located on the rotor, while an asynchronous generator has special grooves for winding on the shaft.

Synchronous generators are used when it is necessary to supply current with high starting power for a short period of time, in excess of the rated one. Application a synchronous generators more provided for in everyday life, for energy supply household appliances, as well as for lighting, since electrical energy is generated with virtually no distortion.

How is a generator different from an engine?

Summing up, it is important to note that the functioning of engines and generators is based on general principle electromagnetic induction. Data construction electrical machines similar, however there is a difference in the rotor configuration.

The main difference is functional purpose generator and engine: the engine generates mechanical energy by consuming electrical energy, and the generator, on the contrary, generates electrical energy by consuming mechanical or other type of energy.

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Stages

It has two main stages:

• rotor manufacturing
• creating a generator

These works have practically nothing in common with each other, since it is necessary to make the nodes of the system different in essence and purpose. For the manufacture of both elements, improvised mechanisms and devices are used that can be used or converted into the necessary unit. One of the options for creating a generator, often used in the manufacture of a wind generator, is the manufacture of an asynchronous electric motor, which most successfully and efficiently solves the problem. Let's consider the question in more detail:

Making a generator from an asynchronous motor

An asynchronous motor is the best "blank" for the manufacture of a generator. He has for this best performance in terms of resistance to short circuit, less picky about the ingress of dust or dirt. In addition, asynchronous generators produce more “clean” energy, the clear factor (the presence of higher harmonics) for these devices is only 2% versus 15% for synchronous generators. Higher harmonics contribute to engine heating and knock down the rotation mode, so their small number is a big plus of the design.

Asynchronous devices do not have rotating windings, which largely eliminates the possibility of their failure or damage from friction or shorting.

Also an important factor is the presence of a voltage of 220V or 380 V on the output windings, which allows you to connect consumption devices directly to the generator, bypassing the current stabilization system. That is, as long as there is wind, the devices will work in the same way as from the network.

The only difference from the operation of the full complex is the termination of operation immediately after the wind subsides, while the batteries included in the kit feed the consuming devices using their capacity for some time.

How to remake a rotor

The only change that is made to the design of an asynchronous motor when it is converted into a generator is the installation of permanent magnets on the rotor. To obtain a greater current, the windings are sometimes rewound with a thicker wire, which has less resistance and gives top scores, but this procedure is not critical, you can do without it - the generator will work.

Induction motor rotor does not have any windings or other elements, being, in fact, an ordinary flywheel. The rotor is processed in lathe metal, you can't do without it. Therefore, when creating a project, it is necessary to immediately resolve the issue of technical support for the work, find a familiar turner or an organization involved in such work. The rotor must be reduced in diameter by the thickness of the magnets that will be installed on it.

READ ALSO: Using a wind generator for light wind - Onipko rotor

There are two ways to mount magnets:

• manufacturing and installation of a steel sleeve, which is put on a rotor previously reduced in diameter, after which magnets are attached to the sleeve. This method makes it possible to increase the strength of the magnets, the field density, which contributes to a more active formation of EMF
• reduction in diameter only by the thickness of the magnets plus the necessary working clearance. This method is easier, but requires more installation strong magnets, best of all - neodymium, which have a much greater force and create a powerful field.

The installation of magnets is carried out along the lines of the rotor structure, i.e. not the will of the axis, but somewhat displaced in the direction of rotation (these lines are clearly visible on the rotor). The magnets are arranged according to the alternation of poles and fixed on the rotor with glue (recommended epoxy resin). After it dries, you can assemble the generator, which our engine has now become, and proceed to the test procedures.

Tests of the newly created generator

This procedure allows you to find out the degree of performance of the generator, empirically determine the rotor speed required to obtain the desired voltage. Usually resort to the help of another engine, for example, an electric drill with an adjustable chuck speed. By rotating the rotor of the generator with a voltmeter or a light bulb connected to it, they check what speeds are needed for the minimum and what is the maximum power limit of the generator in order to obtain data on the basis of which the windmill will be created.

For test purposes, you can connect any consumption device (for example, a heater or a lighting device) and make sure that it works. This will help to remove all emerging issues and make any changes, if necessary. For example, sometimes there are situations with a “sticking” of a rotor that does not start in light winds. This occurs when the magnets are unevenly distributed and is corrected by disassembling the generator, disconnecting the magnets, and reattaching them in a more uniform configuration.

Upon completion of all work, a fully working generator appears, which now needs a source of rotation.

Unfortunately, domestic power supply organizations do not keep their word. Their contracts signed with consumers are worth nothing. The supply of electricity outside of large cities is unstable, the quality of the supplied current is low (meaning voltage), so residents of small cities and towns always have candles in stock, kerosene lamps, and the most advanced install gasoline current generators. This article will offer another option, which will be indicated by the question, how to make an electric generator with your own hands? Let's look at one version of this device.

Electric generator from walk-behind tractor

Residents of suburban villages have long used walk-behind tractors. After all, today it is, so to speak, the most reliable assistant, without which work in the garden or garden is not carried out. True, like all this type of tools, the walk-behind tractor fails. You can restore it, but as practice shows, it is better to buy a new one.

The owners of the instrument are in no hurry to say goodbye to it, so each owner country house there is one old copy in the pantry. It will be possible to use it in the design of an electric generator with a voltage of 220/380 volts. It will create torque for the current generator, which can be adapted as a conventional induction motor. In this case, a powerful electric motor will be required (at least 15 kW, with a shaft speed of 800-1600 rpm). Why such a large motor power?

Do homemade generator for a couple of light bulbs it makes no sense, because the issue of fully providing a country house with electricity is being solved. And with an electric motor of small power, it will not work to get enough electricity. Although it all depends on the total power of household appliances and lighting at home. Indeed, in small dachas, there is nothing but a refrigerator with a TV. Therefore, advice - first calculate the power of the house, then choose an electric motor-generator.

Assembly of the generator

So, in order to assemble a gasoline generator with your own hands with a voltage of 220 volts, you need to install a walk-behind tractor and an electric motor on one frame so that their shafts are parallel. The thing is that the rotation from the walk-behind tractor to the electric motor will be transmitted using two pulleys. One will be mounted on the shaft of a gasoline engine, the second on the shaft of an electric one. In this case, it is necessary to correctly select the diameters of the pulleys. It is these dimensions that select the frequency of rotation of the electric motor. This indicator must be equal to the nominal, which is indicated on the equipment tag. slight deviation in big side within 10-15% is welcome.

When the mechanical part of the assembly is completed, the pulleys connected by the belt will be installed, you can proceed to the electrical part.

• First, the windings of the electric motor are connected in a star pattern.
• Secondly, the capacitors connected to each winding must form a triangle.
• Thirdly, the voltage in such a circuit is removed between the end of the winding and the midpoint. It is here that a current of 220 volts is obtained, and between the windings of 380 volts.

Attention! Installed in wiring diagram capacitors must have the same capacitance. In this case, the capacitance value is selected depending on the power of the electric motor. It is this ratio that will support the correct operation of the current generator itself, but especially its start-up.

For information, we give the ratio of motor power to the capacitance of capacitors:

• 2 kW - 60 uF.
• 5 kW - 140 uF.
• 10 kW - 250 uF.
• 15 kW - 350 uF.

Pay attention to some helpful tips given by experts.

• If the electric motor gets warm, then it is necessary to change the capacitors to elements with a reduced capacity.
• Typically, for homemade power generators, capacitors with a voltage of at least 400 volts are used.
• Usually one capacitor is enough for a resistive load.
• If there is a need to use all three phases of the electric motor to power the house, then a three-phase transformer must be installed in the network.

And one moment. If you are faced with the problem of how to organize heating using a home-made electric generator, then the engine from the walk-behind tractor will be small here (meaning the power of the device). The best option- this is an engine from a car, for example, from an Oka or a Zhiguli. Many may say that such equipment will cost a pretty penny. Nothing like this. You can buy a used car today for a penny, so the costs will be miserable.

Advantages and disadvantages

So, what are the advantages of this device:

• You console yourself with the thought that you made it yourself. That is, you are proud of yourself.
• Financial costs are reduced to a minimum. Homemade unit will cost much less than its factory counterpart.
• If all assembly steps are carried out correctly, then the electrical equipment assembled by your hands can be considered reliable and quite productive.

A few negative points of this kind of devices.

• If you are new to electrics or are trying, without delving into all the subtleties and nuances of assembly, to make a current generator, then you will fail. The time and money spent by you will be considered thrown to the wind.

In principle, this is the only drawback, which inspires optimism.

Other generator designs

The petrol option is not the only one. You can make the motor shaft rotate different ways. For example, using a windmill or a water pump. Not the most simple designs, but it is they that allow moving away from the consumption of energy in the form of gasoline.

For example, it is also easy to assemble a hydrogenerator with your own hands. If a river flows near the house, its water can be used as a force to rotate the shaft. To do this, a wheel with many containers is installed in its channel. With this design, it is possible to create a flow of water that will rotate a turbine attached to an electric motor shaft. And the larger the volume of each tank, the more often they are installed (the number increases), the greater the power of the water flow. In fact, this is a kind of generator voltage regulator.

With wind generators, things are a little different, because wind loads are not constant values. The rotation of the windmill, which is transmitted to the shaft of the electric motor, must be regulated, adjusting to the required value of the rotational speed of the electric motor shaft. Therefore, in this design, the voltage regulator is a conventional mechanical gearbox. But here, as they say, a double-edged sword. If the wind reduces gusts, a step-up gearbox is needed, if, on the contrary, it increases, a reduction gearbox is needed. This is the complexity of the construction of a wind power generator.

Conclusion on the topic

Summing up, you need to understand that homemade power generators are not a panacea. It is better to ensure that the village is constantly fed electricity. It is difficult to achieve this, but you can get compensation for the inconvenience through the courts. And the money already received should be directed to the purchase of a factory gasoline generator. True, you will have to take into account the consumption of expensive fuel (gasoline). But if there is a desire to assemble an electric generator with your own hands, then delve into the topic and try.