How to make an asynchronous motor as a generator with your own hands. Do-it-yourself wind generator on an asynchronous motor

An asynchronous (induction) generator is an electrical product that operates on alternating current and has the ability to reproduce electrical energy. Distinctive feature is the high rotor speed.

This parameter is significantly higher than that of the synchronous analogue. The operation of an asynchronous machine is based on its ability to convert mechanical energy into electricity. Allowable voltage is 220V or 380V.

Areas of use

Today, the scope of application of asynchronous devices is quite wide. They are used:

• in the transport industry (braking system);
• in agricultural work (units that do not require power compensation);
• in everyday life (motors of autonomous water or wind power plants);
• for welding work;
• to provide uninterruptible power supply the most important equipment, such as medical refrigerators.

In theory, it is quite possible to convert an asynchronous motor into an asynchronous generator. To do this, you need:

• have a clear understanding of electric current;
• carefully study the physics of generating electricity from mechanical energy;
• provide the required conditions for the occurrence of current on the stator winding.

Specifics of the device and principle of operation

The main elements of asynchronous generators are the rotor and stator. The rotor is a short-circuited part, the rotation of which produces an electromotive force. Aluminum is used to make conductive surfaces. The stator is equipped with a three-phase or single-phase winding arranged in a star shape.

As shown in the photo of an asynchronous type generator, other components are:

• cable input (it leads out electricity);
• temperature sensor (needed to monitor the heating of the winding);
• flanges (purpose – a tighter connection of elements);
• slip rings (not connected to each other);
• regulating brushes (they trigger a rheostat, which allows you to regulate the rotor resistance);
• short-circuit device (used if it is necessary to forcefully stop the rheostat).

The operating principle of asynchronous generators is based on the conversion of mechanical energy into electrical energy. The movement of the rotor blades leads to the generation of electric current on its surface.

As a result, a magnetic field is formed that induces single- and three-phase voltage on the stator. The generated energy can be regulated by changing the load on the stator windings.

Features of the scheme

The generator circuit of an asynchronous motor is quite simple. It does not require special skills. When you start the development without connecting to the power supply, rotation will begin. Having reached the appropriate frequency, the stator winding will begin to generate current.

If you install a separate battery of several capacitors, the result of such manipulation will be a leading capacitive current.

The parameters of the generated energy are influenced specifications generator and the capacity of the capacitors used.

Types of asynchronous motors

It is customary to distinguish the following types of asynchronous generators:

With squirrel-cage rotor. A device of this type consists of a stationary stator and a rotating rotor. The cores are steel. An insulated wire is placed in the grooves of the stator core. A rod winding is installed in the grooves of the rotor core. The rotor winding is closed by special jumper rings.

With wound rotor. This product is quite expensive. Requires specialized maintenance. The design is similar to that of a generator with a squirrel-cage rotor. The difference is in the use insulated wire as windings.

The ends of the winding are attached to special rings placed on the shaft. Brushes pass through them, connecting the wire with the rheostat. An asynchronous generator with a wound rotor is less reliable.

Converting the engine into a generator

As stated earlier, it is acceptable to use an induction motor as a generator. Let's take a look at a small master class.

You will need a motor from a regular washing machine.

• Let's reduce the thickness of the core and make several blind holes.
• Let's cut a strip from sheet steel, the size of which is equal to the size of the rotor.
• We will install neodymium magnets (at least 8 pieces). Let's secure them with glue.
• Cover the rotor with a sheet of thick paper and secure the edges with adhesive tape.
• We coat the rotor end with a mastic composition for sealing purposes.
• Fill the free space between the magnets with resin.
• After the epoxy has cured, paper layer we remove.
• Sand the rotor using sandpaper.
• Using two wires, we connect the device to the working winding and remove unnecessary wires.
• If desired, we replace the bearings.

We install the current rectifier and mount the charging controller. Our DIY asynchronous motor generator is ready!

More detailed instructions How to make an asynchronous type generator can be found on the Internet.

• Protect the generator from mechanical damage and precipitation.
• Make a special protective case for the assembled machine.
• Remember to regularly monitor generator parameters.
• Don't forget to ground the unit.
• Avoid overheating.

Photos of asynchronous generators

The article describes how to build a three-phase (single-phase) 220/380 V generator based on asynchronous electric motor alternating current. 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 become predominantly widespread both in industry and in agriculture, as well as in everyday life.

Asynchronous electric motors are the simplest and most reliable to operate. Therefore, in all cases where this 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 stationary 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 electrical steel sheets insulated from one another. A winding made of insulated wire is placed in the grooves of the stator core. A rod winding is placed into 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 made like a stator winding is placed in the slots of a phase-wound rotor. The ends of the winding are brought to slip rings mounted on the shaft. Brushes slide along the rings, connecting the winding to a starting or control rheostat.

Asynchronous electric motors with a wound rotor are more expensive devices, require qualified maintenance, are less reliable, and therefore are used only in those industries where they cannot be done without them. For this reason, they are not very common, and we will not consider them further.

A current flows through the stator winding connected to a three-phase circuit, creating a rotating magnetic field. Magnetic power lines The rotating field of the stator crosses the rods of the rotor winding and induces electromotive force (EMF) in them. Under the influence of this EMF, current flows in the short-circuited rotor rods. Magnetic fluxes arise around the rods, creating a general magnetic field of the rotor, which, interacting with the rotating magnetic field of the stator, creates a force causing the rotor to rotate in the direction of rotation magnetic field stator.

The rotor rotation frequency is slightly less than the rotation frequency 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 highly reliable, good performance qualities and correspond to world standards.

Autonomous asynchronous generators are three-phase machines that convert the mechanical energy of the prime mover into alternating current electrical energy. Their undoubted advantage over other types of generators is the absence of a commutator-brush mechanism and, as a consequence, greater durability and reliability.

Operation of an asynchronous electric motor in generator mode

If an asynchronous motor disconnected from the network is set into rotation from any prime mover, then in accordance with the reversibility principle electric machines When the synchronous rotation speed is reached, a certain EMF is generated at the terminals of the stator winding under the influence of the residual magnetic field. If you now connect a battery of capacitors C to the terminals of the stator winding, then a leading capacitive current will flow in the stator windings, which is in this case magnetizing.

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

Standard circuit for connecting an asynchronous electric motor as a generator.

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

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

Q = 0.314 U 2 C 10 -6 ,

where C is the capacitance of the capacitors, μF.

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 capacity. To maintain a constant voltage with increasing load, it is necessary to increase the capacitor capacity, that is, connect additional capacitors. This circumstance must be considered as a disadvantage of the asynchronous generator.

The rotation frequency of an asynchronous generator in normal mode must exceed the asynchronous one by a slip value S = 2...10%, and correspond to the synchronous frequency. Not fulfilling 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 consumers of electricity: electric pumps, washing machines, devices with transformer input.

A decrease in the generated frequency is especially dangerous, 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.

An ordinary asynchronous squirrel-cage electric motor of appropriate power can be used as an asynchronous generator 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" and "Dream" types with a power of up to 2 kW;
• electric irons (power 850…1000 W).

I would especially like 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 electricity consumers.

If 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 working with electrodes with a diameter of 4 mm, then in the heaviest mode - “cutting” metal, the total power consumed by it can reach 10...12 kW, respectively, the power of an asynchronous generator should be within 11...13 kW.

As a three-phase bank of capacitors, it is good to use so-called reactive power compensators, designed to improve cosφ in industrial lighting networks. Their typical designation: KM1-0.22-4.5-3U3 or KM2-0.22-9-3U3, which stands for in the following way. KM - impregnated cosine capacitors mineral oil, the first number 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 three-phase or single-phase version, U3 (moderate climate of the third category).

When self-made batteries, you should use capacitors such as MBGO, MBGP, MBGT, K-42-4, etc. for an operating voltage of at least 600 V. Electrolytic capacitors cannot be used.

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

Two-phase mode of an asynchronous generator.

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

This circuit should be used when there is no need to obtain three-phase voltage. This switching option reduces the working capacity of the capacitors, reduces the load on the primary mechanical engine in mode idle move etc. 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 use: from washing machines such as "Oka", "Volga", watering pumps "Agidel", "BTsN", etc. Their capacitor battery can connect in parallel with the working winding, or use an existing phase-shifting capacitor connected to the starting winding. The capacity of this capacitor may need to be increased slightly. Its value will be determined by the nature of the load connected to the generator: active loads (electric furnaces, light bulbs, electric soldering irons) require a small capacity, inductive loads (electric motors, televisions, refrigerators) require more.

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

Now a few words about the primary mechanical engine, 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 motor 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 motor should be 7.5...10 kW. Using a transmission mechanism, the speed of the mechanical engine and the generator are matched 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 generator power by increasing the speed of the mechanical engine.

Each autonomous power plant must contain minimum required attachments: AC voltmeter (with a scale up to 500 V), 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 makes it easier to start a mechanical engine, and also allows you to quickly reduce the temperature of the generator windings; after completion of work, the rotor of the unexcited generator is rotated for some time by the mechanical engine. This procedure extends the active life of the generator windings.

If using a generator it is intended to power equipment that is normally connected to an alternating current network (for example, lighting in a residential building, household electrical appliances), then it is necessary to provide a two-phase switch that will disconnect this equipment from the industrial network while the generator is operating. Both wires must be disconnected: “phase” and “zero”.

In conclusion, some general advice.

1. The alternator is a hazardous device. Use 380 V only when absolutely necessary; in all other cases, use 220 V.

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

3. Pay attention to the thermal mode of the generator. He "does not like" idling. The thermal load can be reduced by more carefully selecting the capacitance of the exciting capacitors.

4. Make no mistake about the amount of electrical current produced by the generator. If one phase is used when operating a three-phase generator, then its power will be 1/3 of the total power of the generator, if two phases will be 2/3 of the total power of the generator.

5. The frequency of the alternating current produced by the generator can be indirectly controlled by the output voltage, which in the “no-load” mode should be 4...6% higher than the industrial value of 220/380 V.

All household appliances that are used today for household purposes are powered by electricity. That is, it turns out that the electric current becomes the main mechanical work devices. But this addiction has back side– it is possible to obtain electrical energy from mechanical energy. And many craftsmen take advantage of this by creating a generator from an asynchronous motor with their own hands.

Everyone who has a house outside the city is faced with the problem of inconsistent power supply. Let's face it, this is the number one problem of holiday villages. Generators running on gasoline or diesel fuel help get out of this situation. True, such energy devices are not a cheap pleasure, so many summer residents assemble generators with their own hands, using an asynchronous motor.

How does an asynchronous generator work?

So, as mentioned above, an asynchronous motor can operate in generator mode only if it is provided with rotor torque and the capacitor group is correctly selected and connected.

As for torque, there are a huge number of designs and devices that can create this torque. Here are just a few examples.

• It can be any gasoline or diesel engine low power. Many craftsmen use chainsaws or walk-behind tractors for this. To increase the rotation speed of the electric motor rotor, it is necessary to calculate the ratio of the diameter of the pulleys installed on the rotor and the gas engine shaft. Rotation is transmitted using a belt; a chain is not used in this case due to high speed rotation.
• You can create mechanical energy using water by installing a blade structure under its flow, similar to the propeller of a ship or boat.
• There is an option using a windmill. Typically, such devices are installed in steppe zones where wind is always present.

These are the three main ways to produce electric current through an induction motor.

Attention! All experts assure that perfect option the use of an engine for mechanical energy is one with a so-called eternal idle. That is, the rotation speed does not change and is a constant value. In addition, you will have to increase the rotation speed of the electric motor shaft, which will differ from the nominal one by an increase of 10%.

You can find out the nominal rotation speed on the tag or in the device passport. Its unit of measurement is rpm. If you have not found this indicator, then you can determine it by connecting the motor to the power supply network, having first installed a tachometer on the shaft.

Now regarding the capacitors and the electric motor connection diagram. Firstly, there is a certain dependence of the capacitor capacity on the generator power. Here it is in the table below.

Secondly, the capacitance of the capacitors on each engine trim is the same. Thirdly, keep in mind that high capacity can lead to overheating of the electric motor. Therefore, strictly adhere to the ratio according to the table. Fourthly, installation and assembly of the capacitor group is a responsible matter, so be careful. Isolation is very important in this case.

Advice! The capacitors must be connected to each other according to a triangle diagram. And the windings are star circuit.

By the way, here is a diagram below for switching on an electric motor as a generator.

And one moment. The generator from a squirrel-cage asynchronous motor produces a very high voltage. Therefore, if you need 220V voltage, it is recommended to install a step-down transformer after it. It is also possible to convert single-phase electric motors of low power, which are used in household appliances. Of course, they will also be low-power, but using them to turn on a light bulb or connect a modem will not be a problem. By the way, novice home craftsmen begin their activities as an electrician with such small devices. Their circuitry is simple, the parts are accessible, and the assembled device itself is practically safe.

1. A generator made from an asynchronous motor is a high-risk device. And it doesn’t matter what kind of motor it has that transmits mechanical energy. In any case, care must be taken to ensure safe operation. The easiest way is to properly insulate the device.
2. If an asynchronous generator will be used periodically as a source of electricity, then it must be equipped with measuring instruments. Typically a tachometer and a voltmeter are used for this.
3. Of course, there should be two buttons in the unit circuit: “ON” and “OFF”.
4. A prerequisite is grounding.
5. Please also take into account the fact that the power of an asynchronous generator usually differs from the power of the electric motor itself by 30-50%. This is due to losses during the conversion of mechanical energy into electrical energy.
6. Pay attention also to temperature regime operation. Just like an internal combustion engine, the generator will heat up.

Conclusion on the topic

Making a generator from a regular asynchronous motor with your own hands is not a problem. Here it is important to comply with all the requirements that we described above. A small inaccuracy and everything can go wrong. In any case, it will no longer be possible to obtain a current of 220 volts, and even if it does, the unit itself will not work for long.

The invention relates to the field of electrical engineering and power engineering, in particular to methods and equipment for generating electrical energy, and can be used in autonomous systems power supply, automation and household appliances, in aviation, sea and road transport.

Due to the non-standard generation method, and original design motor-generator, generator and electric motor modes are combined in one process and are inextricably linked. As a result, when a load is connected, the interaction of the magnetic fields of the stator and rotor forms a torque, which coincides in direction with the torque created by the external drive.

In other words, as the power consumed by the generator load increases, the rotor of the motor-generator begins to accelerate, and the power consumed by the external drive decreases accordingly.

Rumors have been circulating on the Internet for a long time that a generator with a Gram ring armature was capable of generating more electrical energy than was expended in mechanical energy, and this was due to the fact that there was no braking torque under load.

The results of experiments that led to the invention of the motor generator.

Rumors have been circulating on the Internet for a long time that a generator with a Gram ring armature was capable of generating more electrical energy than was expended in mechanical energy and this was due to the fact that there was no braking torque under load. This information prompted us to conduct a series of experiments with ring winding, the results of which we will show on this page. For experiments, 24 pieces of independent windings with the same number of turns were wound on a toroidal core.

1) Initially, the winding weights were connected in series, the load terminals were located diametrically. In the center of the winding was located permanent magnet with the possibility of rotation.

After the magnet was set in motion using the drive, the load was connected and the drive revolutions were measured with a laser tachometer. As one would expect, the speed of the drive motor began to fall. The more power the load consumed, the more the speed dropped.

2) For a better understanding of the processes occurring in the winding, a milliammeter was connected instead of the load direct current.
When the magnet rotates slowly, you can observe the polarity and magnitude of the output signal in a given position of the magnet.

From the figures it can be seen that when the magnet poles are opposite the winding terminals (Fig. 4;8), the current in the winding is 0. When the magnet is positioned when the poles are in the center of the winding, we have a maximum current value (Fig. 2;6).

3) At the next stage of experiments, only one half of the winding was used. The magnet also rotated slowly, and the readings of the device were recorded.

The instrument readings completely coincided with the previous experiment (Figure 1-8).

4) After that, an external drive was connected to the magnet and it began to rotate at maximum speed.

When the load was connected, the drive began to gain momentum!

In other words, during the interaction of the poles of the magnet and the poles formed in the winding with the magnetic core, when current passes through the winding, a torque appears, directed along the direction of the torque created by the drive motor.

Figure 1, the drive is strongly braking when the load is connected. Figure 2, when a load is connected, the drive begins to accelerate.

5) To understand what is happening, we decided to create a map of the magnetic poles that appear in the windings when current passes through them. To achieve this, a series of experiments were carried out. The windings were connected in different ways, and direct current pulses were applied to the ends of the windings. In this case, a permanent magnet was attached to the spring and was located in turn next to each of the 24 windings.

Based on the reaction of the magnet (whether it was repelled or attracted), a map of the manifesting poles was compiled.

From the pictures you can see how the magnetic poles appeared in the windings when turned on differently (the yellow rectangles in the pictures are the neutral zone of the magnetic field).

When changing the polarity of the pulse, the poles, as expected, changed to the opposite, therefore different variants switching on windings are drawn with one power polarity.

6) At first glance, the results in Figures 1 and 5 are identical.

With more detailed analysis, it became clear that the distribution of the poles around the circle and the “size” of the neutral zone are quite different. The force with which the magnet was attracted or repelled from the windings and magnetic circuit is shown by gradient shading of the poles.

7) When comparing the experimental data described in paragraphs 1 and 4, in addition to the fundamental difference in the response of the drive to connecting the load, and a significant difference in the “parameters” of the magnetic poles, other differences were identified. During both experiments, a voltmeter was turned on in parallel with the load, and an ammeter was turned on in series with the load. If the instrument readings from the first experiment (point 1) are taken as 1, then in the second experiment (point 4), the voltmeter reading was also equal to 1. The ammeter reading was 0.005 from the results of the first experiment.

8) Based on what was stated in the previous paragraph, it is logical to assume that if a non-magnetic (air) gap is made in the unused part of the magnetic circuit, then the current strength in the winding should increase.

After the air gap was made, the magnet was again connected to the drive motor and spun to maximum speed. The current strength actually increased several times, and began to be approximately 0.5 of the results of the experiment under point 1,
but at the same time a braking torque appeared on the drive.

9) Using the method described in paragraph 5, a map of the poles of this structure was compiled.

10) Let's compare two options

It is not difficult to assume that if the air gap in the magnetic core is increased, the geometric arrangement of the magnetic poles according to Figure 2 should approach the same arrangement as in Figure 1. And this, in turn, should lead to the effect of accelerating the drive, which is described in paragraph 4 (when connecting load, instead of braking, an additional torque is created to the drive torque).

11) After the gap in the magnetic circuit was increased to the maximum (to the edges of the winding), when a load was connected instead of braking, the drive began to pick up speed again.

In this case, the map of the poles of the winding with the magnetic core looks like this:

Based on the proposed principle of generating electricity, it is possible to design alternating current generators that, when increasing the electrical power in the load, do not require an increase in the mechanical power of the drive.

Operating principle of the Motor Generator.

According to the phenomenon of electromagnetic induction, when the magnetic flux passing through a closed circuit changes, an emf appears in the circuit.

According to Lenz's rule: An induced current arising in a closed conducting circuit has such a direction that the magnetic field it creates counteracts the change in magnetic flux that caused the current. In this case, it does not matter exactly how the magnetic flux moves in relation to the circuit (Fig. 1-3).

The method of exciting EMF in our motor-generator is similar to Figure 3. It allows us to use Lenz’s rule to increase the torque on the rotor (inductor).

1) Stator winding
2) Stator magnetic circuit
3) Inductor (rotor)
4) Load
5) Rotor rotation direction
6) Central line of the magnetic field of the inductor poles

When the external drive is turned on, the rotor (inductor) begins to rotate. When the beginning of the winding is crossed by the magnetic flux of one of the poles of the inductor, an emf is induced in the winding.

When a load is connected, current begins to flow in the winding and the poles of the magnetic field that arises in the windings, according to E. H. Lenz’s rule, are directed towards meeting the magnetic flux that excited them.
Since the winding with the core is located along a circular arc, the magnetic field of the rotor moves along the turns (circular arc) of the winding.

In this case, at the beginning of the winding, according to Lenz’s rule, a pole appears identical to the pole of the inductor, and at the other end it is opposite. Since like poles repel and opposite poles attract, the inductor tends to take a position that corresponds to the action of these forces, which creates an additional moment directed along the direction of rotation of the rotor. The maximum magnetic induction in the winding is achieved at the moment when the center line of the inductor pole is opposite the middle of the winding. With further movement of the inductor, the magnetic induction of the winding decreases, and at the moment the central line of the inductor pole leaves the winding, it is equal to zero. At the same moment, the beginning of the winding begins to cross the magnetic field of the second pole of the inductor, and according to the rules described above, the edge of the winding from which the first pole begins to move away begins to push it away with increasing force.

Drawings:
1) Zero point, the poles of the inductor (rotor) are symmetrically directed to different edges of the winding in the winding EMF = 0.
2) The central line of the north pole of the magnet (rotor) crossed the beginning of the winding, an EMF appeared in the winding, and accordingly a magnetic pole identical to the pole of the exciter (rotor) appeared.
3) The rotor pole is at the center of the winding and the EMF is at its maximum value in the winding.
4) The pole approaches the end of the winding and the emf decreases to a minimum.
5) Next zero point.
6) Center line south pole enters the winding and the cycle repeats (7;8;1).

It was decided to convert an asynchronous motor as a generator for a windmill. This modification is very simple and affordable, so homemade designs In wind turbines you can often see generators made from asynchronous motors.

The modification consists of cutting the rotor under the magnets, then the magnets are usually glued to the rotor according to a template and filled in epoxy resin so as not to fly off. They also usually rewind the stator with a thicker wire to reduce too much voltage and increase the current. But I didn’t want to rewind this motor and it was decided to leave everything as is, just convert the rotor to magnets. A three-phase asynchronous motor with a power of 1.32 kW was found as a donor. Below is a photo of this electric motor.

asynchronous motor conversion into a generator The rotor of the electric motor was machined to lathe to the thickness of the magnets. This rotor does not use a metal sleeve, which is usually machined and placed on the rotor under the magnets. The sleeve is needed to enhance magnetic induction, through it the magnets close their fields by feeding each other from underneath and the magnetic field does not dissipate, but goes all the way to the stator. This design uses fairly strong magnets measuring 7.6*6mm in the amount of 160 pieces, which will provide a good EMF even without a sleeve.

First, before gluing the magnets, the rotor was marked into four poles, and the magnets were placed at a bevel. The motor was four-pole and since the stator did not rewound, there should also be four magnetic poles on the rotor. Each magnetic pole alternates, one pole is conventionally “north”, the second pole is “south”. The magnetic poles are made at intervals, so the magnets are grouped closer together at the poles. After being placed on the rotor, the magnets were wrapped with tape for fixation and filled with epoxy resin.

After assembly, the rotor felt sticking, and when the shaft rotated, sticking was felt. It was decided to remake the rotor. The magnets were knocked together with epoxy and placed again, but now they are more or less evenly placed throughout the rotor, below is a photo of the rotor with magnets before being filled with epoxy. After filling, the sticking decreased somewhat and it was noticed that the voltage dropped slightly when the generator rotated at the same speed and the current increased slightly.

After assembling the finished generator, it was decided to twist it with a drill and connect something to it as a load. A 220 volt 60 watt light bulb was connected, at 800-1000 rpm it burned at full intensity. Also, to test what the generator was capable of, a 1 kW lamp was connected; it burned at full intensity and the drill was not strong enough to turn the generator.

At idle, at maximum drill speed of 2800 rpm, the generator voltage was more than 400 volts. At approximately 800 rpm the voltage is 160 volts. We also tried connecting a 500-watt boiler, after a minute of twisting the water in the glass became hot. These are the tests that the generator, which was made from an asynchronous motor, passed.

Afterwards, a stand with a rotating axis was welded for the generator to mount the generator and tail. The design is made according to the scheme with the wind head moving away from the wind by folding the tail, so the generator is offset from the center of the axis, and the pin behind is the pin on which the tail is placed.

Here is a photo of the finished wind generator. The wind generator was installed on a nine-meter mast. When the wind was strong, the generator produced an idle voltage of up to 80 volts. They tried connecting a two-kilowatt tenn to it, but after a while the tenn became warm, which means the wind generator still has some power.

Then a controller for the wind generator was assembled and the battery was connected through it for charging. The charging current was quite good, the battery quickly began to make noise, as if it were being charged from a charger.

The data on the electric motor wiring diagram said 220/380 volts 6.2/3.6 A. This means the generator resistance is 35.4 Ohm delta/105.5 Ohm star. If he charged a 12-volt battery according to the scheme of connecting the generator phases in a triangle, which is most likely, then 80-12/35.4 = 1.9A. It turns out that with a wind of 8-9 m/s, the charging current was approximately 1.9 A, which is only 23 watt/hour, not much, but maybe I was wrong somewhere.

Such large losses are due to the high resistance of the generator, so the stator is usually rewound with a thicker wire to reduce the resistance of the generator, which affects the current strength, and the higher the resistance of the generator winding, the lower the current strength and the higher the voltage.