Previously, we have already considered, based on the popularity of this topic, we propose to create a wind generator from an asynchronous motor. It is necessary to slightly alter the electric motor; read on to find out how to do this.
To make a generator for a wind generator, we will use an asynchronous motor.
To change the engine, you need to machine the rotor for the magnets, glue the magnets to the rotor and fill it with epoxy. In addition, the stator must be rewound with a thicker wire in order to lower the voltage and increase the current. But we decided to leave the engine untouched and just rework the rotor. We used a three-phase unit, its power is 1.32 kilowatts.
The motor rotor is being machined lathe. Note that in the case of this rotor we did not use a sleeve, which is usually worn under magnets. Its presence is explained by the need to strengthen the magnetic induction; the magnets close the fields through the sleeve, and dissipation does not occur magnetic field, everything is directed towards the stator. This system involves the use of very strong magnets, the size of which is 7.6x6 millimeters. 160 pieces are taken, with their help they provide sufficient electric motor force even without a sleeve.
Initially, before gluing the magnets, the rotor is marked into 4 poles, and the magnets are arranged with a bevel. The motor had four poles, due to the fact that there was no rewinding of the stator, 5 magnetic poles must be present. Each pole is alternated, “south” and “north”. The poles need certain pauses; the magnets are located more densely here. After we placed the magnets, they were wrapped with tape and fixed with epoxy.
The rotor was sticking, and there was also a problem during shaft rotation. We made some changes, removed the magnets and resin, and then re-placed the elements. At the same time, emphasis was placed on greater uniformity during installation. After filling, we realized that the sticking became less noticeable, in addition, the voltage during the rotation of the generator at the same speed became less, and the current indicator increased slightly.
Then we assembled a special controller, and then connected the battery to charging using it. A good current indicator was provided, but noise appeared, similar to what happens when using charging devices.
We hope our instructions on how to create a wind generator for your home with your own hands from an asynchronous motor will help you make a wind generator.
In an effort to obtain autonomous sources of electricity, experts have found a way to remake a three-phase asynchronous electric motor with their own hands alternating current to the generator. This method has a number of advantages and some disadvantages.
Appearance of an asynchronous electric motor
The section shows the main elements:
A detailed disassembly of the asynchronous electric motor, indicating all the parts, is shown in the figure below.
Detailed disassembly of an asynchronous motor
Advantages of generators converted from asynchronous motors:
As a disadvantage, one can note the difficulty of calculating the capacitance of capacitors connected to the windings; in fact, this is done experimentally.
Therefore, it is difficult to achieve the maximum power of such a generator; there are difficulties with power supply to electrical installations that have great importance starting current, on circular electric saws with three-phase AC motors, concrete mixers and other electrical installations.
The operation of such a generator is based on the principle of reversibility: “any electrical installation that converts electrical energy into a mechanical one, the process can be reversed.” The principle of operation of generators is used; rotation of the rotor causes an EMF and the appearance of an electric current in the stator windings.
Based on this theory, it is obvious that an asynchronous electric motor can be converted into an electric generator. In order to consciously carry out reconstruction, it is necessary to understand how the generation process occurs and what is required for this. All motors driven by alternating current are considered asynchronous. The stator field moves slightly ahead of the rotor magnetic field, pulling it along with it in the direction of rotation.
To obtain the reverse process, generation, the rotor field must advance the movement of the stator magnetic field, ideally rotating in opposite direction. This is achieved by connecting a large capacitor to the power supply network; to increase the capacity, groups of capacitors are used. The capacitor unit is charged by accumulating magnetic energy (an element of the reactive component of alternating current). The charge of the capacitor is in phase opposite to the current source of the electric motor, so the rotation of the rotor begins to slow down, the stator winding generates current.
How to practically convert an asynchronous electric motor into a generator with your own hands?
To connect the capacitors, you need to unscrew the top cover of the boron (box), where the contact group is located, switching the contacts of the stator windings and the power wires of the asynchronous motor are connected.
Open boron with contact group
The stator windings can be connected in a “Star” or “Triangle” configuration.
Connection circuits "Star" and "Triangle"
The nameplate or product data sheet shows possible connection diagrams and motor parameters for various connections. Indicated:
Engine parameters indicated on the nameplate
In a three-phase generator from an asynchronous electric motor, which is made by hand, the capacitors are connected in a similar “Triangle” or “Star” circuit.
The connection option with a “Star” ensures the starting process of generating current at lower speeds than when connecting the circuit in a “Triangle”. In this case, the voltage at the generator output will be slightly lower. Delta connection provides a slight increase in output voltage, but requires higher rpm when starting the generator. In a single-phase asynchronous electric motor, one phase-shifting capacitor is connected.
Connection diagram of capacitors on a generator in a “Triangle”
Capacitors of the KBG-MN model or other brands of at least 400 V non-polar are used; bipolar electrolytic models are not suitable in this case.
What does a poleless capacitor of the KBG-MN brand look like?
Calculation of capacitor capacity for the motor used
| Generator rated output power, kW | Estimated capacity in, µF |
|---|---|
| 2 | 60 |
| 3,5 | 100 |
| 5 | 138 |
| 7 | 182 |
| 10 | 245 |
| 15 | 342 |
In synchronous generators, the generation process is excited on the armature windings from the current source. 90% of asynchronous motors have squirrel-cage rotors, without winding; excitation is created by a residual static charge in the rotor. It is enough to create an EMF at the initial stage of rotation, which induces current and recharges the capacitors through the stator windings. Further recharging already comes from the generated current; the generation process will be continuous as long as the rotor rotates.
It is recommended to install the automatic load connection to the generator, sockets and capacitors in a separate closed panel. Lay the connecting wires from the boron generator to the switchboard in a separate insulated cable.
Even when the generator is not working, you must avoid touching the capacitor terminals of the socket contacts. The charge accumulated by the capacitor remains for a long time and can cause an electric shock. Ground the housings of all units, motor, generator, control panel.
When installing a generator with a motor with your own hands, you must take into account that the specified number of rated revolutions of the asynchronous electric motor used at idle is greater.
Scheme of a motor-generator on a belt drive
On an engine of 900 rpm at idle speed there will be 1230 rpm, in order to obtain sufficient power at the output of a generator converted from this engine, you must have a number of revolutions 10% higher than idle speed:
1230 + 10% = 1353 rpm.
Belt drive is calculated using the formula:
Vg = Vm x Dm\Dg
Vg – required generator rotation speed 1353 rpm;
Vm – motor rotation speed 1200 rpm;
Dm – pulley diameter on the motor is 15 cm;
Dg – diameter of the pulley on the generator.
Having a 1200 rpm motor where the pulley is Ø 15 cm, all that remains is to calculate Dg - the diameter of the pulley on the generator.
Dg = Vm x Dm/ Vg = 1200 rpm x 15cm/1353 rpm = 13.3 cm.
How to make a generator from an asynchronous electric motor?
This homemade generator excludes the use capacitor units. The source of the magnetic field, which induces EMF and creates current in the stator winding, is built on permanent neodymium magnets. In order to do this yourself, you must sequentially perform the following steps:
What does the rotor of an asynchronous motor look like?
Installing magnets on the rotor
An interesting application option is when an electric generator based on an asynchronous electric motor is used in a self-feeding electric motor-generator circuit. When part of the power generated by the generator goes to the electric motor, which spins it. The rest of the energy is spent on the payload. By implementing the principle of self-feeding, it is practically possible to provide the house with autonomous power supply for a long time.
For a wide range of electricity consumers, buy powerful diesel power plants like TEKSAN TJ 303 DW5C with an output power of 303 kVA or 242 kW does not make sense. Low-power gasoline generators expensive, best option do it yourself wind generators or a self-powered motor-generator device.
Using this information, you can assemble a generator with your own hands, using permanent magnets or capacitors. This type of equipment is very useful for country houses, in field conditions, as an emergency power source when there is no voltage in industrial networks. Fully equipped house with air conditioning, electric stoves and heating boilers, powerful motor circular saw they won't pull it. You can temporarily provide electricity to essential household appliances, lighting, refrigerators, TVs and others that do not require large amounts of power.
An asynchronous wind generator is a great way to extract energy from a frequent satellite weather conditions- wind. Such a device can not only be purchased, but also made with your own hands. What are the advantages of an asynchronous motor and how to build it? This will be discussed in this article.
An asynchronous generator has a number of advantages.
It is quite simple to convert an asynchronous motor as a generator, so this method of acquiring energy is quite common.
rewinding the stator with a thick wire to increase the current and reduce high voltage, although this is not always done. Before gluing the magnets, the rotor can be marked into four poles, and then the magnets can be placed at a bevel. Each pole of the magnet alternates. Such
magnetic poles made at intervals. After the magnets are located on the rotor, they need to be wrapped with tape and filled with epoxy resin. However, when assembling the device, you may feel the rotor sticking. To fix this, you need to remake the rotor. This process involves knocking down the magnets along with the resin, after which they need to be reinstalled, but now this needs to be done more evenly throughout the rotor. After
refill sticking should be reduced. This will also affect the rotation voltage, which will drop slightly, as well as the current, which will increase.
After assembly, the generator can be twisted with a drill and something connected to it as a load.
To do this, you can connect a lamp to a certain number of watts and watch how it burns, at full heat or not. In addition, you can connect the boiler and observe when and to what extent the water heats up. If all these tests are successful, the induction motor is good to operate, but there is something else that needs to be done.
The efficiency, reliability and simplicity of wind generators using an asynchronous motor cannot leave indifferent a person who wants to make the most of wind energy. What is especially attractive is that you can make such a design yourself, so its work will be even more attractive.
To make a wind generator with a power of up to 1 kW yourself, there is no need to purchase special equipment. This problem can be easily solved if you have an asynchronous motor. Moreover, the indicated power will be quite sufficient to create conditions for the operation of individual household appliances and connect street lighting in the garden at the dacha.
If you make a windmill with your own hands, then you will have a free source of energy that you can use at your discretion. Any House master is able to independently manufacture a wind generator based on an asynchronous motor.
The generating set that will generate electricity includes the following main elements:
Operation of homemade wind turbines carried out by analogy with wind generators which are used in industry. The main purpose is to generate alternating voltage, for which kinetic energy is transformed into electrical energy. The wind drives a rotor-type wind wheel, as a result of which the resulting energy flows from it to the generator. Moreover, usually the role of the latter is performed by an asynchronous motor.
As a result of the current generated by the generator, the latter enters the battery, which is equipped with a module and a charge controller. From there it is sent to a DC inverter, the source of which is the power grid. As a result it is possible to create an alternating voltage, the characteristics of which are suitable for use for domestic purposes (220 V 50 Hz).
A controller is used to transform AC voltage into DC voltage. It is with its help that the batteries are charged. In some cases, inverters are capable of performing the functions of an uninterruptible power supply. In other words, in case of problems with the power supply, they can use batteries or generators as a power source for household devices.
To make a wind generator, it is enough to have an asynchronous motor, which will have to be redone. At the same time, you will have to stock up on a number of materials:
The generator has the following characteristics:
Most often, installing a generator yourself is done using a three-bladed wind wheel, reaching a diameter of about 2 m. The decision to increase the number of blades or their length does not lead to improved performance. Regardless of the chosen option regarding the configuration, dimensions and shape of the blades, preliminary calculations should first be performed.
During self-installation you need to pay attention to such a parameter as the condition of the soil in the area where the support and guy wires will be placed. The mast is installed by digging a hole no more than 0.5 m deep, which must be filled with concrete mortar.
Network connection carried out in a strictly defined order: the batteries are connected first, followed by the wind generator itself.
The rotation of the wind generator can be carried out in a horizontal or vertical plane. In this case, the choice is usually made on the vertical plane, which is related to the structural design. It is permissible to use Darrieus and Savonius models as rotors.
The installation design must use sealing gaskets or a cap. Thanks to this solution, moisture will not harm the generator.
An open location should be chosen to place the mast and support. A suitable height for the mast is 15 m. In this case masts are the most widely used, whose height does not exceed 5-7 m.
It is optimal if a self-made wind generator functions as a backup power source.
These installations have restrictions on their use, since their operation is only possible in those regions where the wind speed reaches about 7-8 m/s.
Before you start creating a windmill with your own hands, do accurate calculations. In some cases, difficulties arise with processing asynchronous motor components;
A windmill cannot be created without electrical modules, as well as a series of experiments.
Although, always you can purchase a ready-made asynchronous generator, you can go the other way and save money by making it yourself. There will be no difficulties here. The only thing you need to do is prepare the necessary tools.
These are all the operations that must be performed when arranging an engine-based generator. Then you can proceed to its installation. Please be aware that when using a device equipped with a squirrel-cage rotor, you will receive a current of high voltage. For this reason, to achieve a value of 220 V, you will need a step-down transformer.
The question of wind power generators is very relevant in our time. Many European manufacturers offer wind generators different power, but they are not cheap. And the entire system, including a wind power generator, an inverter for converting DC to AC and rechargeable batteries, this is a very expensive pleasure that is unlikely to pay for itself in the near future. Such wind installations cannot be afforded by an ordinary consumer of electrical energy.
From all that has been said, we can conclude that the most pressing issue is to reduce the cost of generating electricity from wind.
When using permanent magnet generators, you can get a not very high voltage; as a rule, it does not exceed 10 V. And besides, the wind speed is not a constant value. Installations on such generators must always be equipped with batteries and an inverter. But based on the fact that the most optimal batteries are 150 A/h batteries, it is unlikely that anyone will want to get involved with such an expensive project (for example, the battery of the PT-76 tank weighs 65 kg and is designed for 140 A/h).
Both automobile generators and synchronous motors were used as generators. But both options have the same drawback: the engine rotor speed is too high, and this in turn leads to an increase in the gear ratio, and hence the dimensions of the wind wing. You can also add instability of the operating frequency and the difficulty of stabilizing the output voltage, and in the case of a synchronous motor, even larger dimensions and weight. To stabilize the output voltage, you can use batteries and an inverter, but this will lead to the circuit that is currently used by European manufacturers, which will not be discussed here because it is very expensive.
During long searches and experiments, preference was given to a generator based on an asynchronous motor with a squirrel-cage rotor. When using this scheme, many advantages and only one disadvantage were identified.
Advantages: small dimensions and weight with sufficiently high power; no need for excitation voltage; if you use a low-speed engine, then the rotor power can be reduced; the output frequency is practically independent of the rotor speed.
Flaw: This generator must not be overloaded.
The connection diagram for an asynchronous motor with a squirrel-cage rotor is shown in Figure No. 1. When the motor rotor rotates, a residual magnetic field acts on one of the stator windings. In this case, there is a slight electricity, which charges one of the capacitors C1-C3. Due to the fact that the phase of the voltage on the capacitor lags behind, a magnetic field of greater magnitude appears on the rotor, which acts on the next winding. Accordingly, the next capacitor will be charged at a higher voltage. This process continues until the generator rotor enters saturation (1...1.15 s). After this, you can turn on the B2 machine and use the energy generated by the generator. Moreover, for normal operation of the engine in generator mode, the load power should be no more than 80% of the engine used as a generator. The remaining 20% is used to maintain the voltage on the capacitors, i.e. maintaining the generator in working condition. If exceeded this condition the voltage on the capacitors will disappear, which means the magnetic field on the armature will disappear, which will lead to the disappearance of voltage at the terminals of the B2 machine. Moreover, this happens almost instantly.
This has its drawbacks and its advantages. The disadvantage is that reapplying voltage is possible only when the cause of the overload is eliminated and the B2 circuit breaker is turned off. The generator will sleepily enter operating mode (in 1...1.5 s). After this, you can turn on B2 and use the energy. An advantage is the fact that it is almost impossible to burn the generator, since the voltage at its terminals disappears instantly within 0.1...0.5 s. The output voltage has a sinusoidal shape and is completely suitable for further use. The generator output frequency is 46…60 Hz, which in most cases is sufficient for home use. Due to the instability of the voltage at the voltage output, it is necessary to install a stabilizer (a description of the circuit and operation is described in an additional article).
The capacity of additional capacitors is indicated in Table No. 1, per kilowatt of the specified motor power, and for operation with a load - additional capacitance for each kilowatt of load.
Table No. 1 Capacity of capacitors included in the phases, in microfarads per 1 kW of power.
|
Voltage between phases |
Main capacitance (uF) |
||
|
At idle |
With active load |
Under reactive load |
|
For example, there is a 3 kW motor. It is supposed to connect a reactive load (electric motor, welding machine), with a total power of approximately 2 kW. In this case, we want the voltage between the phases to be 380. This means that the capacitance of capacitor C1 will be (35) + (26) microfarads. Since C1=C2=C3, we will need three capacitors with a capacity of 30 μF. If there are no capacitors of the required capacity, then you can connect capacitors in parallel with a smaller capacity. Capacitors must be paper or metal-paper for a voltage of at least 450 V, and preferably 650 V. It is better to turn on the generator at a voltage between phases of 220 V, and between zero and phase 127 V. This is due to the fact that for normal operation of the generator there should be no phase imbalance exceed. With this scheme, it will be possible to unload the generator as much as possible. In addition, powering incandescent light bulbs and some heating devices It is better to supply with direct current.
For the generator it is necessary to use a low-speed motor with a squirrel-cage rotor. It is best to use a 360...720 rpm engine, but a 910 rpm engine will also work. This is caused by the need to rotate the rotor at approximately twice the speed specified in the engine data sheet, and by a reduction in the gearbox gear ratio.
The wind generator itself can be made in any design convenient for you. The following design is proposed here. The principle of operation is shown in Figure 3 and does not need explanation. The wind turbine (Figure No. 4) consists of a wind wing 1, a support 2 and the generator itself 3. The support is rigidly concreted and reinforced with three tension cables 4. The support can be made of wood, concrete, or metal. You can use a support that is used to transmit electricity over a distance, or your own. Best used as stretch marks steel rope with a diameter of 10..12 mm. The crutches to which the guy wires are attached must be well concreted. The frame of the wind turbine wings can be made from pipes with a diameter of 1 inch; its drawing is shown in Figure No. 5. Ailerons can be made from steel rod with a diameter of 6mm. A thick-walled pipe with a diameter of 2..2.5 inches was used as a driving shaft, into the lower end of which a shaft 300...400 mm long was pressed. At the lower end of the shaft there is a groove for the pulley. The bearings are spherical with tapered clamps brand 2000810 with a corresponding housing.
After assembly, the wing must be balanced. The balanced wing can be attached to the support using any in a convenient way, but the main thing is that the fastening is sufficiently rigid and reliable. It was experimentally established that the best material To cover the wing, a polyethylene film with a thickness of 80...120 microns is used. It is quite durable, lightweight and cheap, allowing you to do away with the brake mechanism, which, by the way, is in this case unacceptable, since strong wind the wing will be destroyed. You need to cover it with plastic film in several layers, soldering it at the seams, using a soldering iron through a piece of plastic film. The welded seam must be equal and strong.
A gearbox is used to drive the generator shaft. You can use a gearbox of any system except a worm gear. As already mentioned, the generator shaft needs to be rotated at approximately twice the speed, and the wind turbine shaft rotates at a speed of 500 rpm at a wind speed of 5 m/s. Hence the limitation on using the engine as a generator. The best option there may be a 360 rpm engine, but you can also use a 720 rpm engine. When using an engine, the wing height can be increased by 500 mm. It is not recommended to increase the width of the wing, since this reduces the rotation speed; the same should not be decreased, since with an increase in the rotation speed, the power will greatly decrease, and the law of decrease is not linear.
When selecting a gearbox, you need to be guided by following rules: for the nominal speed of the wind turbine wing you need to take the value of 500 rpm, which corresponds to a wind speed of 5 m/s, the engine shaft rotation speed increases by 2.3, then by simple calculations we obtain the transmission coefficient. The bracket itself is easy to attach to the support using six studs. Fastening with a gear reducer is much easier. It is not recommended to make the wind turbine shaft too long, as it may simply twist. The entire structure must be grounded. The grounding resistance should be no more than 2 ohms. At the foot it is necessary to place a cabinet in which it is necessary to place capacitors C1-C3, circuit breakers B1-B2, diodes V1-V6, a voltage stabilizer, a control machine, four batteries and a powerful voltage converter to provide energy during calm periods. The automatic control ensures switching of power circuits depending on the load and wind speed. A powerful voltage converter provides battery charging while the generator is idling, as well as powering the network from batteries in the absence of wind or when the voltage on the generator is very low. When there is no voltage and the batteries are discharged, the automatic control system supplies energy from the standard network.
The cable used to connect the generator and the power cabinet must be three-phase with a core cross-section of no more than. The cables used to connect the cabinet to consumers can be the same. The grounding bus must have a cross-section of at least.
Attention! All installation work must be carried out with the B1 circuit breaker turned off and the capacitors C1-C3 discharged.
