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How to make an electric generator at home. Asynchronous motor as a generator

The desire to make your home completely autonomous is inherent in every owner of a country cottage and even a small cottage. But if there are no special problems with water and sewerage, then centralized electrical networks often throw up unpleasant moments. Therefore, many are trying to acquire autonomous mini-power plants that could support the operation of household appliances in the event of a network failure.

But such equipment is very expensive and not everyone can afford it. How to act in such a situation? You can buy one unit for several houses in a pool, but then it must have more power, and, therefore, a high price. There is a cheaper option - to assemble an electric generator with your own hands, using available tools for this. Can anyone make such a device? Let's try to find out by analyzing the information on the network.

What are generators and where are they used?

It is a device capable of producing electricity by burning fuel. They are either single or three phase. Moreover, the latter are distinguished by the ability to work with various loads.

They are used as a backup and in some cases a permanent source of power supply and are designed for operation:

Types and features of their application

Technological equipment of this class is classified according to the following parameters:

Sphere of use;
type of fuel burned;
The number of phases;
Power.

Let's start with the scope. Depending on this factor, generators are divided into household and professional ones, although a simple electric generator can be assembled with your own hands. The former are usually made in the form of a compact power unit and have a power of 0.7 to 25 kW. They are equipped with an internal combustion engine running on gasoline or diesel fuel and equipped with an air cooling system. Such devices are used as backup energy sources for household appliances and power tools, as well as a self-powered electric generator assembled by oneself.

They are distinguished by their low weight and low noise level, therefore they are widely used in private households. The operation and maintenance of such units is not difficult and everyone can cope with it, as well as assemble an electric generator with their own hands.

We watch the video, a little about the generators, their types and advantages:

Professional equipment is designed to work as a permanent source of energy supply. Typically, such generators are used in medical institutions and office buildings, as well as in the construction industry during emergency and other work. Units of this class have significant weight and are not distinguished by quiet operation, which greatly complicates their transportation and selection of a place for installation. But at the same time, they have a higher motor resource and reliability when operating in extreme conditions. The advantages of such electric generators include economical fuel consumption.

The power of industrial power plants can exceed 100 kW, which allows them to be used as backup power sources for electrical equipment of large enterprises. The disadvantage of these units is complex maintenance.

The next parameter used in the classification is the type of fuel:

Petrol;
Diesel;

The first ones have a small power range, but at the same time they are mobile and easy to use, like do-it-yourself ones. They are used as backup sources, as they have a small motor resource and the high cost of the energy received.

Diesel units have a wide range of capacities and can be used to supply public institutions and even small villages. However, they are not distinguished by their compact dimensions and quiet operation, therefore they must be installed on a reinforced foundation in a separate room.

They are mainly used in industrial facilities. They are distinguished by high environmental friendliness and low cost of generated energy.

Power plants also differ in the number of phases per:

one;
Three.

The former are suitable for devices with single-phase power supply in the respective networks. The latter can serve as a source of energy for various appliances and are installed in houses with a three-phase network wiring.

Device and principle of operation

Principle of operation

A machine capable of converting mechanical energy into electrical energy is called a power plant. Its principle of operation is based on the phenomenon of electromagnetic induction, well known to everyone from the course of school physics.

It states that an EMF is formed in a conductor moving in a magnetic field and crossing the lines of force. Therefore, it can be considered as a source of electricity.

But since this method is not entirely convenient for practical use, it was somewhat changed in generators using the rotational movement of the conductor. In theoretical terms, power plants are a system of electromagnets and conductors. But structurally, they consist of internal combustion engines and generators.

Do-it-yourself power plant diagram

Many, trying to save money, try as much as possible to create home-made equipment, such as a generator. The fact that this device is necessary in every home does not need to be explained to anyone, but an industrial model is expensive.

To get similar equipment in a cheaper version, you will have to assemble it yourself. There are various schemes of do-it-yourself electric generators: from the simplest ones - windmills, to more complex ones - made on the basis of internal combustion engines. Let's consider some of them.

Windmill - simple option

Vyatryak scheme

You can assemble such a unit from improvised materials. It can be used both on a hike and in the country and belongs to self-assembled fuel-free electric generators. It will require:

DC electric motor (it will play the role of a generator);
Carriage knot and driven sprocket from an adult bike;
Roller chain from a motorcycle;
Duralumin 2 mm thick.

All this does not require large expenditures, and perhaps even find it for free in your garage. How to make an electric generator on your own, you can see in the video below. Assembly also does not require special knowledge. A chain sprocket is mounted on the motor shaft.

Watch the video, detailed assembly instructions:

In this case, it can be attached to a bicycle frame. The blades of the windmill are made slightly curved and up to 80 cm long. Even with a slight wind, such a device is capable of producing from 4 to 6 amperes and a voltage of 14 V. Even an engine from an old scanner can be taken as a generator for a windmill. This is the simplest electric generator that you can assemble with your own hands.

Power plant based on an old generator from a walk-behind tractor

Before looking for a scheme for a homemade device, decide which option will be the most affordable for you. Perhaps you can find a generator from an old walk-behind tractor and, on its basis, assemble a device that can provide power to electric lamps located in several rooms.

As a generator for such an installation, an asynchronous motor of the AIR series with a speed of up to 1600 rpm and a power of up to 15 kW is suitable. It is connected with the help of pulleys and a drive belt with a motor removed from a walk-behind tractor. The diameter of the pulleys must be such that the rotational speed of the electric motor used as a generator is 15% higher than the passport value.

Watch the video for more details on this work:

The motor windings must be connected in a star, and a capacitor is connected in parallel with each pair. The result is a triangle. But to ensure the operation of the generator, it is necessary that all generators have the same capacity.

For the needs of building a private residential building or a summer house, a home master may need an autonomous source of electrical energy, which can be bought in a store or assembled with your own hands from available parts.

Homemade generator is able to run on the energy of gasoline, gas or diesel fuel. To do this, it must be connected to the engine through a shock-absorbing clutch that ensures smooth rotation of the rotor.

If local environmental conditions allow, for example, frequent winds blow or a source of running water is nearby, then you can create a wind or hydraulic turbine and connect it to an asynchronous three-phase motor to generate electricity.

Due to such a device, you will have a constantly working alternative source of electricity. It will reduce energy consumption from public networks and allow savings on its payment.

In some cases, it is permissible to use a single-phase voltage to rotate an electric motor and transmit torque to a home-made generator to create its own three-phase symmetrical network.

How to choose an asynchronous motor for a generator by design and characteristics

Technological features

The basis of a homemade generator is a three-phase asynchronous electric motor with:

phase;
or squirrel-cage rotor.

Stator device

The magnetic circuits of the stator and rotor are made of insulated plates of electrical steel, in which grooves are created to accommodate the winding wires.

The three individual stator windings can be wired in the factory as follows:

stars;
or a triangle.

Their conclusions are connected inside the terminal box and connected with jumpers. The power cable is also installed here.

In some cases, wires and cables can be connected in other ways.

Symmetrical voltages are supplied to each phase of the induction motor, shifted in angle by a third of the circle. They form currents in the windings.

These quantities are conveniently expressed in vector form.

Design features of the rotors

Wound rotor motors

They are provided with a winding modeled on the stator, and the leads from each are connected to slip rings, which provide electrical contact with the start-up and adjustment circuit through pressure brushes.

This design is quite difficult to manufacture, expensive in cost. It requires periodic monitoring of work and qualified maintenance. For these reasons, it makes no sense to use it in this design for a home-made generator.

However, if there is a similar motor and it has no other application, then the conclusions of each winding (those ends that are connected to the rings) can be shorted to each other. In this way, the phase rotor will turn into a short-circuited one. It can be connected according to any scheme considered below.

Squirrel cage motors

Aluminum is poured inside the grooves of the rotor magnetic circuit. The winding is made in the form of a rotating squirrel cage (for which it received such an additional name) with jumper rings short-circuited at the ends.

This is the simplest motor circuit, which is devoid of moving contacts. Due to this, it works for a long time without the intervention of electricians, it is characterized by increased reliability. It is recommended to use it to create a homemade generator.

Designations on the motor housing

In order for a homemade generator to work reliably, you need to pay attention to:

, which characterizes the quality of protection of the body from the effects of the external environment;
power consumption;
speed;
winding connection diagram;
permissible load currents;
Efficiency and cosine φ.

The principle of operation of an induction motor as a generator

Its implementation is based on the method of electric machine reversibility. If the motor is disconnected from the mains voltage, the rotor is forced to rotate at the calculated speed, then EMF will be induced in the stator winding due to the presence of residual energy of the magnetic field.

It remains only to connect a capacitor bank of the appropriate rating to the windings and a capacitive leading current will flow through them, which has the character of a magnetizing one.

In order for the generator to self-excite, and a symmetrical system of three-phase voltages to form on the windings, it is necessary to select the capacitance of the capacitors, which is greater than a certain, critical value. In addition to its value, the design of the engine naturally affects the output power.

For the normal generation of three-phase energy with a frequency of 50 Hz, it is necessary to maintain the rotor speed exceeding the asynchronous component by the amount of slip S, which lies within S=2÷10%. It needs to be kept at the synchronous frequency level.

The deviation of the sinusoid from the standard frequency value will adversely affect the operation of equipment with electric motors: saws, planers, various machine tools and transformers. This has practically no effect on resistive loads with heating elements and incandescent lamps.

Wiring diagrams

In practice, all common methods of connecting the stator windings of an induction motor are used. Choosing one of them creates different conditions for the operation of the equipment and generates a voltage of certain values.

Star schemes

A popular option for connecting capacitors

The connection diagram of an asynchronous motor with star-connected windings for operation as a three-phase network generator has a standard form.

Scheme of an asynchronous generator with connection of capacitors to two windings

This option is quite popular. It allows you to power three groups of consumers from two windings:

two voltage 220 volts;
one - 380.

The working and starting capacitors are connected to the circuit by separate switches.

Based on the same circuit, you can create a home-made generator with capacitors connected to one winding of an induction motor.

triangle diagram

When assembling the stator windings according to the star circuit, the generator will produce a three-phase voltage of 380 volts. If you switch them to a triangle, then - 220.

The three schemes shown above in the pictures are basic, but not the only ones. Based on them, other connection methods can be created.

How to calculate the characteristics of the generator by engine power and capacitor capacitance

To create normal operating conditions for an electric machine, it is necessary to observe the equality of its rated voltage and power in the generator and electric motor modes.

For this purpose, the capacitance of the capacitors is selected taking into account the reactive power Q generated by them at various loads. Its value is calculated by the expression:

Q=2π∙f∙C∙U 2

From this formula, knowing the power of the engine, to ensure full load, you can calculate the capacity of the capacitor bank:

C \u003d Q / 2π ∙ f ∙ U 2

However, the mode of operation of the generator should be taken into account. At idle, the capacitors will unnecessarily load the windings and heat them up. This leads to large energy losses, overheating of the structure.

To eliminate this phenomenon, capacitors are connected in steps, determining their number depending on the applied load. To simplify the selection of capacitors for starting an asynchronous motor in generator mode, a special table has been created.

Generator power (kVA)	Full load mode				Idle mode
	cos φ=0.8		cos φ=1		Q (kvar)	C (uF)
	Q (kvar)	C (uF)	Q (kvar)	C (uF)	Q (kvar)	C (uF)
15	15,5	342	7,8	172	5,44	120
10	11,1	245	5,9	130	4,18	92
7	8,25	182	4,44	98	3,36	74
5	6,25	138	3,4	75	2,72	60
3,5	4,53	100	2,54	56	2,04	45
2	2,72	60	1,63	36	1,27	28

Starting capacitors of the K78-17 series and the like with an operating voltage of 400 volts or more are well suited for use as part of a capacitive battery. It is quite acceptable to replace them with metal-paper counterparts with the corresponding denominations. They will have to be connected in parallel.

It is not worth using models of electrolytic capacitors to work in the circuits of an asynchronous home-made generator. They are designed for DC circuits, and when passing a sinusoid that changes in direction, they quickly fail.

There is a special scheme for connecting them for such purposes, when each half-wave is directed by diodes to its assembly. But it's pretty complicated.

Design

The autonomous device of the power plant must fully provide the operating equipment and be carried out by a single module, including a hinged electrical panel with devices:

measurements - with a voltmeter up to 500 volts and a frequency meter;
switching loads - three switches (one general supplies voltage from the generator to the consumer circuit, and the other two connect capacitors);
protection - eliminating the consequences of short circuits or overloads and), saving workers from insulation breakdown and phase potential entering the case.

Main power redundancy

When creating a home-made generator, it is necessary to provide for its compatibility with the grounding circuit of the working equipment, and for autonomous operation, it must be securely connected to.

If the power plant is created for backup power supply of devices operating from the state network, then it should be used when the voltage is disconnected from the line, and when restored, it should be stopped. To this end, it is enough to install a switch that controls all phases simultaneously or connect a complex automatic system for switching on backup power.

Voltage selection

The 380 volt circuit has an increased risk of human injury. It is used in extreme cases, when it is not possible to get by with a phase value of 220.

Generator overload

Such modes create excessive heating of the windings with subsequent destruction of the insulation. They occur when the currents passing through the windings are exceeded due to:

improper selection of capacitor capacitance;
connection of high power consumers.

In the first case, it is necessary to carefully monitor the thermal regime during idling. With excessive heating, it is necessary to adjust the capacitance of the capacitors.

Features of connecting consumers

The total power of a three-phase generator consists of three parts generated in each phase, which is 1/3 of the total. The current passing through one winding must not exceed the rated value. This must be taken into account when connecting consumers, distribute them evenly over the phases.

When a homemade generator is designed to operate on two phases, then it cannot safely generate electricity more than 2/3 of the total value, and if only one phase is involved, then only 1/3.

Frequency control

The frequency meter allows you to monitor this indicator. When it was not installed in the design of a home-made generator, then you can use the indirect method: at idle, the output voltage exceeds the nominal 380/220 by 4 ÷ 6% at a frequency of 50 Hz.

One of the options for making a home-made generator from an asynchronous motor and its capabilities are shown in their video by the owners of the Maria channel with Alexander Kostenko.

(13 votes, average: 4.5 out of 5)

If the rotor of an asynchronous machine connected to the network with voltage U1 is rotated by means of the primary motor in the direction of the rotating stator field, but at a speed n2>

Why We Use Asynchronous Power Generator

An asynchronous generator is an asynchronous electric machine (el.dvigatel) operating in the generator mode. With the help of a drive motor (in our case, a wind turbine), the rotor of an asynchronous electric generator rotates in the same direction as the magnetic field. In this case, the slip of the rotor becomes negative, a braking torque appears on the shaft of the asynchronous machine, and the generator transfers energy to the network.

To excite the electromotive force in its output circuit, the residual magnetization of the rotor is used. For this, capacitors are used.

Asynchronous generators are not susceptible to short circuits.

An asynchronous generator is simpler than a synchronous one (for example, a car generator): if the latter has inductors placed on the rotor, then the rotor of the asynchronous generator looks like a conventional flywheel. Such a generator is better protected from dirt and moisture, more resistant to short circuits and overloads, and the output voltage of an asynchronous generator has a lower degree of non-linear distortion. This allows you to use asynchronous generators not only to power industrial devices that are not critical to the shape of the input voltage, but also to connect electronic equipment.

It is an asynchronous electric generator that is an ideal current source for devices with an active (ohmic) load: electric heaters, welding converters, incandescent lamps, electronic devices, computer and radio engineering.

Benefits of an asynchronous generator

These advantages include a low clear factor (harmonic coefficient), which characterizes the quantitative presence of higher harmonics in the output voltage of the generator. Higher harmonics cause uneven rotation and useless heating of electric motors. Synchronous generators can have a clear factor of up to 15%, and the clear factor of an asynchronous generator does not exceed 2%. Thus, an asynchronous electric generator produces practically only useful energy.

Another advantage of an asynchronous generator is that it completely lacks rotating windings and electronic parts that are sensitive to external influences and are quite often prone to damage. Therefore, the asynchronous generator is not subject to wear and tear and can serve for a very long time.

At the output of our generators, there is immediately 220/380V AC, which can be used directly to household appliances (for example, heaters), to charge batteries, to connect to a sawmill, and also for parallel operation with a traditional network. In this case, you will pay for the difference consumed from the network and generated by the windmill. Because Since the voltage comes immediately to industrial parameters, then you will not need various converters (inverters) when the wind generator is directly connected to your load. For example, you can directly connect to a sawmill and, in the presence of wind, work as if you simply connected to a 380V network.

If the rotor of an asynchronous machine connected to the network with voltage U1 is rotated by means of the primary motor in the direction of the rotating stator field, but at a speed n2>n1, then the movement of the rotor relative to the stator field will change (compared to the motor mode of this machine), since the rotor will overtake the stator field.

In this case, the slip will become negative, and the direction of the emf. E1 induced in the stator winding, and consequently, the direction of the current I1 will change to the opposite. As a result, the electromagnetic moment on the rotor will also change direction and turn from rotating (in the motor mode) into counteracting (in relation to the torque of the primary engine). Under these conditions, the asynchronous machine will switch from a motor to a generator mode, converting the mechanical energy of the prime mover into electrical energy. In the generator mode of an asynchronous machine, the slip can vary in the range

in this case, the emf frequency asynchronous generator remains unchanged, since it is determined by the rotation speed of the stator field, i.e. remains the same as the frequency of the current in the network, which is connected to the asynchronous generator.

Due to the fact that in the generator mode of the asynchronous machine the conditions for creating a rotating stator field are the same as in the motor mode (in both modes, the stator winding is connected to the network with voltage U1), and it consumes the magnetizing current I0 from the network, then the asynchronous a machine in generator mode has special properties: it consumes reactive energy from the network, which is necessary to create a rotating stator field, but gives active energy to the network, obtained as a result of converting the mechanical energy of the prime mover.

Unlike synchronous, asynchronous generators are not subject to the dangers of falling out of synchronism. However, asynchronous generators are not widely used, which is explained by a number of their disadvantages compared to synchronous generators.

An asynchronous generator can also operate in autonomous conditions, i.e. without being connected to the public network. But in this case, to obtain the reactive power necessary to magnetize the generator, a bank of capacitors is used, connected in parallel with the load on the generator outputs.

An indispensable condition for such operation of asynchronous generators is the presence of residual magnetization of the rotor steel, which is necessary for the process of self-excitation of the generator. Small emf Eres induced in the stator winding creates a small reactive current in the capacitor circuit and, consequently, in the stator winding, which enhances the residual flux Fost. In the future, the self-excitation process develops, as in a parallel excitation DC generator. By changing the capacitance of the capacitors, it is possible to change the magnitude of the magnetizing current, and, consequently, the magnitude of the voltage of the generators. Due to the excessive bulkiness and high cost of capacitor banks, asynchronous generators with self-excitation have not gained distribution. Asynchronous generators are used only in low-power auxiliary power plants, for example, in wind power plants.

DIY generator

In my power plant, the current source is an asynchronous generator driven by a gasoline two-cylinder air-cooled engine UD-25 (8 hp, 3000 rpm). As an asynchronous generator, without any alterations, you can use a conventional asynchronous electric motor with a speed of 750-1500 rpm and a power of up to 15 kW.

The frequency of rotation of the asynchronous generator in normal mode must exceed the nominal (synchronous) value of the number of revolutions of the used electric motor by 10%. This can be done in the following way. The electric motor is connected to the network and the idle speed is measured by a tachometer. The belt drive from the engine to the generator is calculated in such a way as to provide a slightly increased generator speed. For example, an electric motor with a rated speed of 900 rpm idles at 1230 rpm. In this case, the belt drive is calculated to provide a generator speed of 1353 rpm.

The windings of the asynchronous generator in my installation are connected with a “star” and produce a three-phase voltage of 380 V. To maintain the nominal voltage of the asynchronous generator, it is necessary to correctly select the capacitance of the capacitors between each phase (all three capacitances are the same). To select the desired capacity, I used the following table. Before acquiring the necessary skill in operation, you can check the heating of the generator by touch in order to avoid overheating. Heating indicates that too much capacitance is connected.

Capacitors are suitable type KBG-MN or others with an operating voltage of at least 400 V. When the generator is turned off, an electric charge remains on the capacitors, therefore, precautions must be taken against electric shock. Capacitors should be securely enclosed.

When working with a 220 V handheld power tool, I use a TSZI step-down transformer from 380 V to 220 V. When a three-phase engine is connected to a power plant, it may happen that the generator does not “master” it from the first start. Then you should give a series of short-term engine starts until it picks up speed, or spin it manually.

Stationary asynchronous generators of this kind, used for electrical heating of a residential building, can be driven by a wind turbine or a turbine installed on a small river or stream, if there are any near the house. At one time in Chuvashia, the Energozapchast plant produced a generator (micro hydroelectric power station) with a capacity of 1.5 kW based on an asynchronous electric motor. V.P. Beltyukov from Nolinsk made a wind turbine and also used an asynchronous motor as a generator. Such a generator can be set in motion using a walk-behind tractor, a minitractor, a scooter engine, a car, etc.

I installed my power plant on a small, light, single-axle trailer - a frame. For work outside the economy, I load the necessary power tools into the machine and attach my installation to it. With a rotary mower I mow hay, with an electric tractor I plow the land, harrow, plant, and spud. For such work, complete with the station, I drive a coil with a four-wire cable KRPT. When winding the cable, one thing should be taken into account. If wound in the usual way, then a solenoid is formed, in which there will be additional losses. To avoid them, the cable must be folded in half and wound on a coil, starting from the bend.

In late autumn, firewood has to be harvested from deadwood for the winter. I also use power tools. At the summer cottage, with the help of a circular saw and a planer, I process material for carpentry.

As a result of a long test of the operation of our Sailing wind generator with a traditional excitation circuit of an asynchronous motor (IM), based on the use of a magnetic starter as a switch, a number of shortcomings were revealed, which led to the creation of the Control Cabinet. Which has become a universal device for turning any Asynchronous Motor into a Generator! Now it is enough to connect the wires from the IM of the engine to our control device and the generator is ready.

How to Turn Any Induction Motor into a Generator - A House Without a Foundation

How to Turn Any Induction Motor Into a Generator - A House Without a Foundation Why We Use an Induction Power Generator An induction generator is a generator

Due to such a device, you will have a constantly working alternative source of electricity. It will reduce energy consumption from public networks and allow savings on its payment.

In some cases, it is permissible to use a single-phase voltage to rotate an electric motor and transmit torque to a home-made generator to create its own three-phase symmetrical network.

How to choose an asynchronous motor for a generator by design and characteristics

Technological features

The basis of a homemade generator is a three-phase asynchronous electric motor with:

Stator device

The magnetic circuits of the stator and rotor are made of insulated plates of electrical steel, in which grooves are created to accommodate the winding wires.

The three individual stator windings can be wired in the factory as follows:

Their conclusions are connected inside the terminal box and connected with jumpers. The power cable is also installed here.

In some cases, wires and cables can be connected in other ways.

Symmetrical voltages are supplied to each phase of the induction motor, shifted in angle by a third of the circle. They form currents in the windings.

These quantities are conveniently expressed in vector form.

Design features of the rotors

Wound rotor motors

Squirrel cage motors

Designations on the motor housing

In order for a homemade generator to work reliably, you need to pay attention to:

IP class, which characterizes the quality of protection of the housing from environmental influences;
power consumption;
speed;
winding connection diagram;
permissible load currents;
Efficiency and cosine φ.

The winding connection diagram, especially for old engines that were in operation, should be called out and checked by electrical methods. This technology is described in detail in the article on connecting a three-phase motor to a single-phase network.

The principle of operation of an induction motor as a generator

It remains only to connect a capacitor bank of the appropriate rating to the windings and a capacitive leading current will flow through them, which has the character of a magnetizing one.

Wiring diagrams

Star schemes

A popular option for connecting capacitors

The connection diagram of an asynchronous motor with star-connected windings for operation as a three-phase network generator has a standard form.

Scheme of an asynchronous generator with connection of capacitors to two windings

This option is quite popular. It allows you to power three groups of consumers from two windings:

The working and starting capacitors are connected to the circuit by separate switches.

Based on the same circuit, you can create a home-made generator with capacitors connected to one winding of an induction motor.

triangle diagram

When assembling the stator windings according to the star circuit, the generator will produce a three-phase voltage of 380 volts. If you switch them to a triangle, then - 220.

The three schemes shown above in the pictures are basic, but not the only ones. Based on them, other connection methods can be created.

How to calculate the characteristics of the generator by engine power and capacitor capacitance

To create normal operating conditions for an electric machine, it is necessary to observe the equality of its rated voltage and power in the generator and electric motor modes.

For this purpose, the capacitance of the capacitors is selected taking into account the reactive power Q generated by them at various loads. Its value is calculated by the expression:

From this formula, knowing the power of the engine, to ensure full load, you can calculate the capacity of the capacitor bank:

There is a special scheme for connecting them for such purposes, when each half-wave is directed by diodes to its assembly. But it's pretty complicated.

Design

The autonomous device of the power plant must fully meet the requirements for the safe operation of operating equipment and be carried out by a single module, including a mounted electrical panel with devices:

measurements - with a voltmeter up to 500 volts and a frequency meter;
switching loads - three switches (one general supplies voltage from the generator to the consumer circuit, and the other two connect capacitors);
protection - an automatic switch that eliminates the consequences of short circuits or overloads and an RCD (residual current device) that saves workers from insulation breakdown and phase potential entering the case.

Main power redundancy

Voltage selection

The 380 volt circuit has an increased risk of human injury. It is used in extreme cases, when it is not possible to get by with a phase value of 220.

Generator overload

Such modes create excessive heating of the windings with subsequent destruction of the insulation. They occur when the currents passing through the windings are exceeded due to:

improper selection of capacitor capacitance;
connection of high power consumers.

In the first case, it is necessary to carefully monitor the thermal regime during idling. With excessive heating, it is necessary to adjust the capacitance of the capacitors.

Features of connecting consumers

When a homemade generator is designed to operate on two phases, then it cannot safely generate electricity more than 2/3 of the total value, and if only one phase is involved, then only 1/3.

Frequency control

How to make a homemade generator from an asynchronous motor, Design and repair of apartments with your own hands

Tips for a home craftsman on making a do-it-yourself home-made generator from an asynchronous three-phase electric motor with diagrams. pictures and videos

How to make a homemade generator from an induction motor

Hello! Today we will consider how to make a homemade generator from an asynchronous motor with your own hands. This question has been of interest to me for a long time, but somehow there was no time to take up its implementation. Now let's do some theory.

If you take and spin an asynchronous electric motor from some prime mover, then following the principle of reversibility of electrical machines, you can make it produce electric current. To do this, you need to rotate the shaft of an asynchronous motor with a frequency equal to or slightly more than the asynchronous frequency of its rotation. As a result of residual magnetism in the magnetic circuit of the electric motor, some EMF will be induced at the terminals of the stator winding.

Now let's take and connect to the terminals of the stator winding, as shown in the figure below, non-polar capacitors C.

In this case, a leading capacitive current will begin to flow through the stator winding. It will be called magnetizing. Those. self-excitation of the asynchronous generator will occur and the EMF will increase. The value of the EMF will depend on the characteristics of both the electrical machine itself and the capacitance of the capacitors. Thus, we have turned an ordinary asynchronous electric motor into a generator.

Now let's talk about how to choose the right capacitors for a homemade generator from an induction motor. The capacity must be selected so that the generated voltage and output power of the asynchronous generator correspond to the power and voltage when it is used as an electric motor. See the data in the table below. They are relevant for excitation of asynchronous generators with a voltage of 380 volts and with a speed of rotation from 750 to 1500 rpm.

With an increase in the load on the asynchronous generator, the voltage at its terminals will tend to fall (the inductive load on the generator will increase). To maintain the voltage at a given level, it is necessary to connect additional capacitors. To do this, you can use a special voltage regulator, which, when the voltage drops at the generator stator terminals, will connect additional capacitor banks with the help of contacts.

The frequency of rotation of the generator in normal mode should exceed the synchronous one by 5-10 percent. That is, if the rotational speed is 1000 rpm, then you need to spin it at a frequency of 1050-1100 rpm.

One big plus of an asynchronous generator is that you can use a conventional asynchronous electric motor as it without alterations. But it is not recommended to get carried away and make generators from electric motors with a power of more than 15-20 kV * A. A homemade generator from an asynchronous motor is an excellent solution for those who do not have the opportunity to use a classic kronotex laminate generator. Good luck with everything and bye!

How to make a homemade generator from an asynchronous motor, DIY repair

How to make a homemade generator from an asynchronous motor Hello everyone! Today we will consider how to make a homemade generator from an asynchronous motor with your own hands. This question has long

The article describes how to build a three-phase (single-phase) 220/380 V generator based on an asynchronous AC motor. A three-phase asynchronous electric motor, invented at the end of the 19th century by the Russian electrical engineer M.O. Dolivo-Dobrovolsky, has now received a predominant distribution in industry, and in agriculture, as well as in everyday life.

Asynchronous electric motors are the simplest and most reliable in operation. Therefore, in all cases where it is permissible under the conditions of the electric drive and there is no need for reactive power compensation, asynchronous AC motors should be used.

There are two main types of asynchronous motors: with squirrel-cage rotor and with phase rotor. An asynchronous squirrel-cage electric motor consists of a fixed part - the stator and a moving part - the rotor, rotating in bearings mounted in two motor shields. The stator and rotor cores are made of separate sheets of electrical steel isolated from one another. A winding made of insulated wire is laid in the grooves of the stator core. A rod winding is placed in the grooves of the rotor core or molten aluminum is poured. Jumper rings short-circuit the rotor winding at the ends (hence the name - short-circuited). Unlike a squirrel-cage rotor, a winding is placed in the grooves of the phase rotor, made according to the type of stator winding. The ends of the winding are led to slip rings mounted on the shaft. Brushes slide along the rings, connecting the winding with a starting or adjusting rheostat.

Asynchronous electric motors with a phase rotor are more expensive devices, require qualified maintenance, are less reliable, and therefore are used only in those industries in which they cannot be dispensed with. For this reason, they are not very common, and we will not consider them further.

A current flows through the stator winding, which is included in a three-phase circuit, creating a rotating magnetic field. The magnetic field lines of the rotating stator field cross the rotor winding rods and induce an electromotive force (EMF) in them. Under the action of this EMF, a current flows in the short-circuited rotor rods. Magnetic fluxes arise around the rods, creating a common magnetic field of the rotor, which, interacting with the rotating magnetic field of the stator, creates a force that makes the rotor rotate in the direction of rotation of the stator magnetic field.

The rotational speed of the rotor is somewhat less than the rotational speed of the magnetic field created by the stator winding. This indicator is characterized by slip S and is for most engines in the range from 2 to 10%.

Most commonly used in industrial installations three-phase asynchronous electric motors, which are produced in the form of unified series. These include a single 4A series with a rated power range from 0.06 to 400 kW, the machines of which are distinguished by high reliability, good performance and meet the level of world standards.

Autonomous asynchronous generators are three-phase machines that convert the mechanical energy of the primary engine into AC electrical energy. Their undoubted advantage over other types of generators is the absence of a collector-brush mechanism and, as a result, greater durability and reliability.

Operation of an asynchronous electric motor in generator mode

If an asynchronous motor disconnected from the network is put into rotation from any primary motor, then, in accordance with the principle of reversibility of electrical machines, when the synchronous speed is reached, some EMF is formed at the terminals of the stator winding under the influence of the residual magnetic field. If now a battery of capacitors C is connected to the terminals of the stator winding, then a leading capacitive current will flow in the stator windings, which in this case is magnetizing.

The battery capacity C must exceed a certain critical value C0, which depends on the parameters of an autonomous asynchronous generator: only in this case the generator self-excites and a three-phase symmetrical voltage system is established on the stator windings. The voltage value depends, ultimately, on the characteristics of the machine and the capacitance of the capacitors. Thus, an asynchronous squirrel-cage motor can be turned into an asynchronous generator.

The standard scheme for switching on an asynchronous electric motor as a generator.

You can choose the capacity so that the rated voltage and power of the asynchronous generator are equal, respectively, to the voltage and power when it works as an electric motor.

Table 1 shows the capacitances of capacitors for excitation of asynchronous generators (U=380 V, 750….1500 rpm). Here reactive power Q is determined by the formula:

Q \u003d 0.314 U 2 C 10 -6,

where C is the capacitance of the capacitors, uF.

Generator power, kVA	Idling
	capacitance, uF	reactive power, kvar	cos = 1		cos = 0.8
			capacitance, uF	reactive power, kvar	capacitance, uF	reactive power, kvar
2,0 3,5 5,0 7,0 10,0 15,0	28 45 60 74 92 120	1,27 2,04 2,72 3,36 4,18 5,44	36 56 75 98 130 172	1,63 2,54 3,40 4,44 5,90 7,80	60 100 138 182 245 342	2,72 4,53 6,25 8,25 11,1 15,5

As can be seen from the above data, the inductive load on the asynchronous generator, which reduces the power factor, causes a sharp increase in the required capacitance. To maintain the voltage constant with increasing load, it is necessary to increase the capacitance of the capacitors, that is, to connect additional capacitors. This circumstance must be considered as a disadvantage of the asynchronous generator.

The rotation frequency of the asynchronous generator in normal mode must exceed the asynchronous one by the amount of slip S = 2 ... 10%, and correspond to the synchronous frequency. Failure to comply with this condition will lead to the fact that the frequency of the generated voltage may differ from the industrial frequency of 50 Hz, which will lead to unstable operation of frequency-dependent electricity consumers: electric pumps, washing machines, devices with a transformer input.

It is especially dangerous to reduce the generated frequency, since in this case the inductive resistance of the windings of electric motors and transformers decreases, which can cause their increased heating and premature failure.

As an asynchronous generator, a conventional asynchronous squirrel-cage electric motor of the appropriate power can be used without any modifications. The power of the electric motor-generator is determined by the power of the connected devices. The most energy intensive of them are:

household welding transformers;
electric saws, electric jointers, grain crushers (power 0.3 ... 3 kW);
electric furnaces of the "Rossiyanka", "Dream" type with a power of up to 2 kW;
electric irons (power 850 ... 1000 W).

I especially want to dwell on the operation of household welding transformers. Their connection to an autonomous source of electricity is most desirable, because. when operating from an industrial network, they create a number of inconveniences for other consumers of electricity.

If a household welding transformer is designed to work with electrodes with a diameter of 2 ... 3 mm, then its total power is approximately 4 ... 6 kW, the power of the asynchronous generator to power it should be within 5 ... 7 kW. If a household welding transformer allows operation with electrodes with a diameter of 4 mm, then in the most difficult mode - "cutting" metal, the total power consumed by it can reach 10 ... 12 kW, respectively, the power of the asynchronous generator should be within 11 ... 13 kW.

As a three-phase capacitor bank, it is good to use the so-called reactive power compensators, designed to improve cosφ in industrial lighting networks. Their type designation: KM1-0.22-4.5-3U3 or KM2-0.22-9-3U3, which is deciphered as follows. KM - cosine capacitors impregnated with mineral oil, the first digit is the size (1 or 2), then the voltage (0.22 kV), power (4.5 or 9 kvar), then the number 3 or 2 means a three-phase or single-phase version, U3 (temperate climate of the third category).

In the case of self-manufacturing of the battery, capacitors such as MBGO, MBGP, MBGT, K-42-4, etc. should be used for an operating voltage of at least 600 V. Electrolytic capacitors cannot be used.

The above option for connecting a three-phase electric motor as a generator can be considered classic, but not the only one. There are other ways that work just as well in practice. For example, when a capacitor bank is connected to one or two windings of an electric motor-generator.

Two-phase mode of the asynchronous generator.

Fig.2 Two-phase mode of an asynchronous generator.

Such a scheme should be used when there is no need to obtain a three-phase voltage. This switching option reduces the working capacitance of the capacitors, reduces the load on the primary mechanical engine in idle mode, and so on. saves "precious" fuel.

As low-power generators that produce an alternating single-phase voltage of 220 V, you can use single-phase asynchronous squirrel-cage electric motors for household purposes: from washing machines such as Oka, Volga, watering pumps Agidel, BCN, etc. They have a capacitor bank connect in parallel with the working winding, or use an existing phase-shifting capacitor connected to the starting winding. The capacitance of this capacitor may need to be slightly increased. Its value will be determined by the nature of the load connected to the generator: an active load (electric furnaces, light bulbs, electric soldering irons) requires a small capacitance, an inductive one (electric motors, televisions, refrigerators) - more.

Fig.3 Low-power generator from a single-phase asynchronous motor.

Now a few words about the prime mover, which will drive the generator. As you know, any transformation of energy is associated with its inevitable losses. Their value is determined by the efficiency of the device. Therefore, the power of a mechanical engine must exceed the power of an asynchronous generator by 50 ... 100%. For example, with an asynchronous generator power of 5 kW, the power of a mechanical engine should be 7.5 ... 10 kW. With the help of the transmission mechanism, the speed of the mechanical engine and the generator are coordinated so that the operating mode of the generator is set at the average speed of the mechanical engine. If necessary, you can briefly increase the power of the generator by increasing the speed of the mechanical engine.

Each autonomous power plant must contain the necessary minimum of attachments: an AC voltmeter (with a scale of up to 500 V), a frequency meter (preferably) and three switches. One switch connects the load to the generator, the other two switch the excitation circuit. The presence of switches in the excitation circuit facilitates the start of a mechanical engine, and also allows you to quickly reduce the temperature of the generator windings, after the end of work, the rotor of an unexcited generator is rotated from a mechanical engine for some time. This procedure extends the active life of the generator windings.

If the generator is supposed to power equipment that is normally connected to the AC mains (for example, residential lighting, household appliances), then it is necessary to provide a two-phase switch that will disconnect this equipment from the industrial network during the operation of the generator. Both wires must be disconnected: "phase" and "zero".

Finally, some general advice.

1. The alternator is a hazardous device. Use 380V only when absolutely necessary, otherwise use 220V.

2. According to safety requirements, the generator must be equipped with grounding.

3. Pay attention to the thermal regime of the generator. He "does not like" idling. It is possible to reduce the thermal load by more careful selection of the capacitance of the excitation capacitors.

4. Make no mistake about the power of the electric current generated by the generator. If one phase is used during the operation of a three-phase generator, then its power will be 1/3 of the total power of the generator, if two phases - 2/3 of the total power of the generator.

5. The frequency of the alternating current generated by the generator can be indirectly controlled by the output voltage, which in the "idle" mode should be 4 ... 6% higher than the industrial value of 220/380 V.

Electric generators are an additional source of energy for the home. In the case of a large distance from the main electrical networks, it may well replace them. Frequent power outages force the installation of alternators.

They are not cheap, is there any point in spending more than 10,000 tr. for the device, if you can make a generator from an electric motor yourself? Of course, some electrical engineering skills and tools will come in handy for this. The main thing is not to spend money.

You can assemble a simple generator with your own hands, it will be relevant if you need to cover a temporary shortage of electricity. For more serious cases, it is not suitable, as it does not have sufficient functionality and reliability.

Naturally, there are many difficulties in the manual assembly process. Required parts and tools may not be available. Lack of experience and skills in such work can be intimidating. But a strong desire will be the main stimulus, and will help to overcome all laborious procedures.

The implementation of the generator and the principle of its operation

Due to electromagnetic induction, an electric current is generated in the generator. This is because the winding moves in an artificially created magnetic field. This is the principle of operation of an electric generator.

The movement of the generator gives the internal combustion engine of low power. It can run on petrol, gas or diesel fuel.

The generator has a rotor and a stator. The magnetic field is created using a rotor. Magnets are attached to it. The stator is the fixed part of the generator and consists of special steel plates and a coil. There is a small gap between the rotor and the stator.

There are two types of generator. The first has a synchronous rotation of the rotor. It has a complex design, and low efficiency. In the second type, the rotor rotates asynchronously. According to the principle of action - it is simple.

Asynchronous motors lose a minimum of energy, while in synchronous generators, the loss rate reaches 11%. Therefore, electric motors with asynchronous rotation of the rotor are very popular in household appliances, and in various factories.

During operation, voltage drops may occur, they have a detrimental effect on household appliances. To do this, there is a rectifier at the output ends.

The asynchronous generator is easy to maintain. Its body is reliable and sealed. You can not be afraid for household appliances that have an ohmic load and are sensitive to voltage drops. High efficiency, and a long period of operation, make the device in demand, moreover, it can be assembled independently.

What do you need to build a generator? First, you need to choose a suitable electric motor. It can be taken from the washing machine. You should not make a stator yourself, it is better to use a ready-made solution where there are windings.

It is worth immediately stocking up with a sufficient amount of copper wires, and insulating materials. Since any generator will produce power surges, you will need a rectifier.

According to the instructions for the generator with your own hands, you need to make a power calculation. In order for the future device to produce the necessary power, it needs to be given a number of revolutions a little more than the rated power.

Let's use a tachometer and turn on the engine in the network, so you can find out the speed of rotation of the rotor. To the obtained value, you need to add 10%, this will prevent the engine from overheating.

Capacitors will help maintain the required voltage level. They are selected depending on the generator. For example, for a power of 2 kW, a capacitance of 60 microfarads is required. You need 3 such parts with the same capacity. To make the device safe, it must be grounded.

Assembly process

Everything is simple here! Capacitors are connected to the electric motor according to the "triangle" scheme. During operation, periodically check the temperature of the case. Its heating may occur due to improperly selected capacitor capacities.

A homemade generator that does not have automatics must be constantly monitored. The heating that occurs over time will reduce efficiency. Then the device needs to be given time to cool down. From time to time, voltage, speed, and current should be measured.

Incorrectly calculated characteristics are not able to give the equipment the necessary power. Therefore, before starting the assembly, you should carry out drawing work, and stock up on diagrams.

It is possible that a homemade device will be accompanied by frequent breakdowns. You should not be surprised at this, since it is almost impossible to achieve a hermetic installation of all elements of an electric generator at home.

So, now I hope it is clear how to make a generator from an electric motor. If there is a desire to design an apparatus, the power of which should be enough for the simultaneous operation of household appliances and lighting lamps, or a construction tool, then you need to add up their power and select the desired engine. It is desirable that it be with a small margin of power.

If you failed during the manual assembly of the generator, do not despair. There are many modern models on the market that do not need constant supervision. They can be of various capacities, and quite economical. There are photos of generators on the Internet, they will help to estimate the dimensions of the device. The only downside is their high cost.