Do-it-yourself self-powered asynchronous motor generator. We remake an asynchronous motor for a generator for a windmill

If necessary, a three-phase asynchronous electric motor with a squirrel-cage rotor can be used as an alternating current generator.

This solution is convenient due to the wide availability of asynchronous motors, and also due to the absence of a collector-brush assembly in such motors, which makes such a generator reliable and durable. If there is a convenient way to bring its rotor into rotation, then it will be enough to connect three identical capacitors to the stator windings to generate electricity. Practice shows that such generators can work for years without the need for maintenance.

Since there is residual magnetization on the rotor, when it rotates, induction EMF will occur in the stator windings, and since capacitors are connected to the windings, there will be a corresponding capacitive current that will magnetize the rotor. With further rotation of the rotor, self-excitation will occur, due to which a three-phase sinusoidal current will be established in the stator windings.

In generator mode, the rotor speed must correspond to the synchronous frequency of the motor, which is higher than its operating (asynchronous) frequency. For example: for the AIR112MV8 motor, the stator winding has 4 pairs of magnetic poles, which means that its nominal synchronous frequency is 750 rpm, but when operating under load, the rotor of this motor rotates at a frequency of 730 rpm, since it is an asynchronous motor. So, in the generator mode, you need to rotate its rotor with a frequency of 750 rpm. Accordingly, for motors with two pairs of magnetic poles, the rated synchronous frequency is 1500 rpm, and with one pair of poles - 3000 rpm.

Capacitors are selected in accordance with the power of the applied asynchronous motor and the nature of the load. The reactive power that capacitors provide in this mode of operation, depending on their capacities, can be calculated by the formula:

For example, there is an asynchronous motor designed for a rated power of 3 kW when operating from a three-phase network with a voltage of 380 volts and a frequency of 50 Hz. This means that the capacitors at full load must provide all this power. Since the current is three-phase, we are talking here about the capacitance of each capacitor. The capacity can be found using the formula:

Therefore, for a given three-phase 3 kW induction motor, the capacitance of each of the three capacitors at full resistive load will be:

Starting capacitors of the K78-17, K78-36 series and the like for a voltage of 400 volts and higher, preferably 600 volts, or metal-paper capacitors of similar ratings are perfect for this purpose.

Speaking about the operating modes of a generator from an asynchronous motor, it is important to note that at idle the connected capacitors will create a reactive current, which will simply heat the stator windings, so it makes sense to make the capacitor units composite and connect the capacitors in accordance with the requirements of a particular load. The no-load current, with this solution, will be significantly reduced, which will unload the system as a whole. Loads of a reactive nature, on the contrary, will require the connection of additional capacitors that exceed the calculated rating due to the power factor characteristic of reactive loads.

It is allowed to connect the stator windings both into a star, to obtain 380 Volts, and into a triangle, to obtain 220 Volts. If there is no need for three-phase current, only one phase can be used by connecting capacitors to only one of the stator windings.

You can work with two windings. Meanwhile, it must be remembered that the power given by each of the windings to the load should not exceed a third of the total power of the generator. Depending on the needs, you can connect a three-phase rectifier, or use direct alternating current. For ease of control, it is useful to organize an indicator stand with measuring instruments - voltmeters, ammeters, and a frequency meter. Automata (circuit breakers) are perfect for switching capacitors.

Particular attention should be paid to safety, take into account the critical currents, and accordingly calculate the cross-sections of all wires. Reliable insulation is also an important safety factor.

A power source is needed to power household appliances and industrial equipment. There are several ways to generate electricity. But the most promising and cost-effective, today, is the generation of current by electric machines. The simplest to manufacture, cheap and reliable in operation turned out to be an asynchronous generator that generates the lion's share of the electricity we consume.

The use of electric machines of this type is dictated by their advantages. Asynchronous power generators, unlike, provide:

• a higher degree of reliability;
• long service life;
• profitability;
• minimum maintenance costs.

These and other properties of asynchronous generators are inherent in their design.

Device and principle of operation

The main working parts of an asynchronous generator are the rotor (moving part) and the stator (stationary). In Figure 1, the rotor is on the right and the stator is on the left. Pay attention to the rotor device. It does not show windings of copper wire. In fact, windings exist, but they consist of aluminum rods short-circuited into rings located on both sides. In the photo, the rods are visible in the form of oblique lines.

The design of short-circuited windings forms the so-called "squirrel cage". The space inside this cage is filled with steel plates. To be precise, aluminum rods are pressed into grooves made in the rotor core.

Rice. 1. Rotor and stator of an asynchronous generator

The asynchronous machine, the device of which is described above, is called a squirrel-cage generator. Anyone who is familiar with the design of an asynchronous electric motor must have noticed the similarity in the structure of these two machines. In fact, they are no different, since the induction generator and the squirrel-cage motor are almost identical, with the exception of additional excitation capacitors used in generator mode.

The rotor is located on a shaft, which sits on bearings clamped on both sides by covers. The whole structure is protected by a metal case. Generators of medium and high power require cooling, so a fan is additionally installed on the shaft, and the case itself is made ribbed (see Fig. 2).

Rice. 2. Asynchronous generator assembly

Operating principle

By definition, a generator is a device that converts mechanical energy into electrical current. It does not matter what energy is used to rotate the rotor: wind, potential energy of water or internal energy converted by a turbine or internal combustion engine into mechanical energy.

As a result of the rotation of the rotor, the magnetic lines of force formed by the residual magnetization of the steel plates cross the stator windings. EMF is formed in the coils, which, when active loads are connected, leads to the formation of current in their circuits.

At the same time, it is important that the synchronous speed of rotation of the shaft slightly (by about 2 - 10%) exceeds the synchronous frequency of the alternating current (set by the number of stator poles). In other words, it is necessary to ensure the asynchrony (mismatch) of the rotational speed by the amount of rotor slip.

It should be noted that the current thus obtained will be small. To increase the output power, it is necessary to increase the magnetic induction. They achieve an increase in the efficiency of the device by connecting capacitors to the terminals of the stator coils.

Figure 3 shows a diagram of a welding asynchronous alternator with capacitor excitation (left side of the diagram). Please note that the excitation capacitors are connected in delta. The right side of the figure is the actual diagram of the inverter welding machine itself.

Rice. 3. Scheme of welding asynchronous generator

There are other, more complex excitation schemes, for example, using inductors and a capacitor bank. An example of such a circuit is shown in Figure 4.

Figure 4. Diagram of a device with inductors

Difference from synchronous generator

The main difference between a synchronous alternator and an asynchronous generator is in the design of the rotor. In a synchronous machine, the rotor consists of wire windings. To create magnetic induction, an autonomous power source is used (often an additional low-power DC generator located on the same axis as the rotor).

The advantage of a synchronous generator is that it generates a higher quality current and is easily synchronized with other alternators of this type. However, synchronous alternators are more sensitive to overloads and short circuits. They are more expensive than their asynchronous counterparts and more demanding to maintain - you need to monitor the condition of the brushes.

The harmonic distortion or clear factor of induction generators is lower than that of synchronous alternators. That is, they generate almost clean electricity. On such currents they work more stable:

• adjustable chargers;
• modern television receivers.

Asynchronous generators provide reliable start of electric motors that require high starting currents. According to this indicator, they are, in fact, not inferior to synchronous machines. They have less reactive loads, which has a positive effect on the thermal regime, since less energy is spent on reactive power. The asynchronous alternator has better output frequency stability at different rotor speeds.

Classification

Squirrel-cage generators are most widely used due to the simplicity of their design. However, there are other types of asynchronous machines: alternators with a phase rotor and devices using permanent magnets that form an excitation circuit.

In Figure 5, for comparison, two types of generators are shown: on the left, on the base, and on the right, an asynchronous machine based on IM with a phase rotor. Even a cursory glance at the schematic images shows the complicated design of the phase rotor. Attention is drawn to the presence of slip rings (4) and the brush holder mechanism (5). The number 3 indicates the grooves for the wire winding, to which it is necessary to apply current to excite it.

Rice. 5. Types of asynchronous generators

The presence of excitation windings in the rotor of an asynchronous generator improves the quality of the generated electric current, but at the same time such advantages as simplicity and reliability are lost. Therefore, such devices are used as an autonomous power source only in those areas where it is difficult to do without them. Permanent magnets in rotors are used mainly for the production of low-power generators.

Application area

The most common use of generator sets with a squirrel-cage rotor. They are inexpensive and require virtually no maintenance. Devices equipped with starting capacitors have decent efficiency indicators.

Asynchronous alternators are often used as an independent or backup power source. They work with them, they are used for powerful mobile and.

Alternators with a three-phase winding confidently start a three-phase electric motor, therefore they are often used in industrial power plants. They can also power equipment in single-phase networks. The two-phase mode allows you to save ICE fuel, since the unused windings are in idle mode.

The scope of application is quite extensive:

• transport industry;
• Agriculture;
• domestic sphere;
• medical institutions;

Asynchronous alternators are convenient for the construction of local wind and hydraulic power plants.

DIY asynchronous generator

Let's make a reservation right away: we are not talking about making a generator from scratch, but about converting an asynchronous motor into an alternator. Some craftsmen use a ready-made stator from a motor and experiment with a rotor. The idea is to use neodymium magnets to make the rotor poles. A blank with glued magnets may look something like this (see Fig. 6):

Rice. 6. Blank with glued magnets

You stick magnets on a specially machined workpiece, planted on the motor shaft, observing their polarity and shift angle. This will require at least 128 magnets.

The finished structure must be adjusted to the stator and at the same time ensure a minimum gap between the teeth and the magnetic poles of the manufactured rotor. Since the magnets are flat, they will have to be ground or turned, while constantly cooling the structure, since neodymium loses its magnetic properties at high temperatures. If you do everything right, the generator will work.

The problem is that in artisanal conditions it is very difficult to make an ideal rotor. But if you have a lathe and are willing to spend a few weeks tweaking and tweaking, you can experiment.

I propose a more practical option - turning an induction motor into a generator (see the video below). To do this, you need an electric motor with suitable power and an acceptable rotor speed. Engine power must be at least 50% higher than the required alternator power. If such an electric motor is at your disposal, proceed to processing. Otherwise, it is better to buy a ready-made generator.

For processing, you will need 3 capacitors of the brand KBG-MN, MBGO, MBGT (you can take other brands, but not electrolytic). Select capacitors for a voltage of at least 600 V (for a three-phase motor). The reactive power of the generator Q is related to the capacitance of the capacitor by the following relationship: Q = 0.314·U 2 ·C·10 -6 .

With an increase in load, reactive power increases, which means that in order to maintain a stable voltage U, it is necessary to increase the capacitance of the capacitors by adding new capacitances by switching.

Video: making an asynchronous generator from a single-phase motor - Part 1

Part 2

In practice, the average value is usually chosen, assuming that the load will not be maximum.

Having selected the parameters of the capacitors, connect them to the terminals of the stator windings as shown in the diagram (Fig. 7). The generator is ready.

Rice. 7. Capacitor connection diagram

Asynchronous generator does not require special care. Its maintenance consists in monitoring the condition of the bearings. At nominal modes, the device is able to work for years without operator intervention.

The weak link is the capacitors. They can fail, especially when their ratings are incorrectly selected.

The generator heats up during operation. If you often connect high loads, monitor the temperature of the device or take care of additional cooling.

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 equipment.

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 were 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 genset

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:

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

They are provided with a winding made according to the stator model, 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:

• 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

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:

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:

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.

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 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

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 reliably connected to the ground loop.

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 turned off from the line, and when it is 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:

1. improper selection of capacitor capacitance;
2. 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, 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.

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

(AG) is the most common AC electric machine, used primarily as a motor.
Only low-voltage AGs (up to 500 V supply voltage) with a power of 0.12 to 400 kW consume more than 40% of all electricity generated in the world, and their annual output is hundreds of millions, covering the most diverse needs of industrial and agricultural production, ship, aviation and transport systems, automation systems, military and special equipment.

These engines are relatively simple in design, very reliable in operation, have sufficiently high energy performance and low cost. That is why the scope of the use of asynchronous motors is constantly expanding both in new areas of technology and instead of more complex electrical machines of various designs.

For example, there has been considerable interest in recent years application of asynchronous motors in generator mode to provide power to both three-phase current consumers and direct current consumers through rectifier devices. In automatic control systems, in a servo drive, in computing devices, asynchronous tachogenerators with a squirrel-cage rotor are widely used to convert the angular velocity into an electrical signal.

Applying Asynchronous Generator Mode

Under certain operating conditions of autonomous power sources, the use of asynchronous generator mode turns out to be the preferred or even the only possible solution, as, for example, in high-speed mobile power plants with a gearless gas turbine drive with a rotation speed n = (9…15)10 3 rpm. The paper describes an AG with a massive ferromagnetic rotor with a power of 1500 kW at n = = 12000 rpm, designed for the autonomous welding complex "Sever". In this case, a massive rotor with longitudinal slots of rectangular cross section does not contain windings and is made of a solid steel forging, which makes it possible to directly articulate the engine rotor in generator mode with a gas turbine drive at peripheral speeds on the rotor surface up to 400 m/s. For a rotor with a laminated core and short circuit with a squirrel cage winding, the permissible circumferential speed does not exceed 200 - 220 m / s.

Another example of the effective use of an asynchronous motor in the generator mode is their long-term use in mini-hydro power plants with a stable load mode.

They are distinguished by ease of operation and maintenance, they are easily switched on for parallel operation, and the shape of the output voltage curve is closer to sinusoidal than that of SG when operating on the same load. In addition, the mass of the AG with a power of 5-100 kW is approximately 1.3–1.5 times less than the mass of the SG of the same power, and they carry a smaller amount of winding materials. At the same time, in a constructive sense, they are no different from conventional IMs and their mass production is possible at electric machine-building plants that produce asynchronous machines.

Disadvantages of the asynchronous mode of the generator, asynchronous motor (HELL)

One of the disadvantages of AD is that they are consumers of significant reactive power (50% or more of the total power) necessary to create a magnetic field in the machine, which must come from the parallel operation of an asynchronous motor in generator mode with a network or from another reactive power source (capacitor bank (BC) or synchronous compensator (SC)) during autonomous operation of the AG. In the latter case, the inclusion of a capacitor bank in the stator circuit in parallel with the load is most effective, although in principle it can be included in the rotor circuit. To improve the operational properties of the asynchronous mode of the generator, capacitors can additionally be included in the stator circuit in series or in parallel with the load.

In all cases Autonomous operation of an asynchronous motor in generator mode Reactive power sources(BC or SC) must provide reactive power to both the AG and the load, which, as a rule, has a reactive (inductive) component (cosφ n< 1, соsφ н > 0).

The mass and dimensions of a capacitor bank or a synchronous compensator can exceed the mass of an asynchronous generator, and only when cosφ n =1 (purely active load) are the dimensions of the SC and the mass of the BC comparable to the size and mass of the AG.

Another, most difficult problem is the problem of stabilizing the voltage and frequency of an autonomously operating AG, which has a "soft" external characteristic.

Using asynchronous generator mode as part of an autonomous system, this problem is further complicated by the instability of the rotor speed. Possible and currently used methods of voltage regulation in the asynchronous mode of the generator.

When designing an AG for optimization calculations, it is necessary to conduct maximum efficiency in a wide range of speed and load changes, as well as to minimize costs, taking into account the entire control and regulation scheme. The design of generators must take into account the climatic conditions of operation of wind turbines, constantly acting mechanical forces on structural elements, and especially powerful electrodynamic and thermal effects during transients that occur during start-ups, power outages, loss of synchronism, short circuits and others, as well as significant gusts wind.

The device of an asynchronous machine, an asynchronous generator

The device of an asynchronous machine with a squirrel-cage rotor is shown on the example of an AM series motor (Fig. 5.1).

The main parts of the IM are a fixed stator 10 and a rotor rotating inside it, separated from the stator by an air gap. To reduce eddy currents, the rotor and stator cores are assembled from separate sheets stamped from electrical steel with a thickness of 0.35 or 0.5 mm. Sheets are oxidized (subjected to heat treatment), which increases their surface resistance.
The stator core is built into the frame 12, which is the outer part of the machine. On the inner surface of the core there are grooves in which the winding 14 is laid. The stator winding is most often made of three-phase two-layer of individual coils with a shortened pitch of insulated copper wire. The beginnings and ends of the phases of the winding are output to the terminals of the terminal box and are designated as follows:

start - CC2, C 3;

ends - C 4, C5, Sat.

The stator winding can be connected with a star (U) or a delta (D). This makes it possible to use the same motor at two different linear voltages, which are in relation to, for example, 127/220 V or 220/380 V. In this case, the U connection corresponds to the inclusion of HELL at a higher voltage.

The assembled rotor core is pressed onto the shaft 15 with a hot fit and is protected from turning with a key. On the outer surface, the rotor core has grooves for laying the winding 13. The rotor winding in the most common IM is a series of copper or aluminum rods located in the grooves and closed at the ends with rings. In engines with a power of up to 100 kW and more, the rotor winding is performed by filling the grooves with molten aluminum under pressure. Simultaneously with the winding, the closing rings are cast along with the ventilation winglets 9. In shape, such a winding resembles a “squirrel cage”.

Phase rotor motor. Asynchronous mode generator a.

For special asynchronous motors, the rotor winding can be performed similarly to the stator winding. A rotor with such a winding, in addition to the indicated parts, has three slip rings mounted on the shaft, designed to connect the winding to an external circuit. HELL in this case is called a motor with a phase rotor or with slip rings.

The rotor shaft 15 combines all elements of the rotor and serves to connect the asynchronous motor with the actuator.

The air gap between the rotor and the stator is from 0.4 - 0.6 mm for low power machines and up to 1.5 mm for high power machines. Bearing shields 4 and 16 of the engine serve as a support for the rotor bearings. Cooling of the asynchronous motor is carried out according to the principle of self-blowing by a fan 5. Bearings 2 and 3 are closed from the outside with covers 1 having labyrinth seals. A box 21 with leads 20 of the stator winding is installed on the stator housing. A plate 17 is fixed on the body, on which the main data of blood pressure are indicated. Figure 5.1 also shows: 6 - shield seat; 7 - casing; 8 - body; 18 - paw; 19 - ventilation duct.

Very often, lovers of outdoor recreation do not want to give up the conveniences of everyday life. Since most of these amenities are connected to electricity, there is a need for an energy source that you can take with you. Someone buys an electric generator, and someone decides to make a generator with their own hands. The task is not easy, but it is quite feasible at home for anyone who has the technical skills and the right equipment.

Generator type selection

Before deciding to make a homemade 220 V generator, you should think about the feasibility of such a decision. You need to weigh the pros and cons and determine what suits you best - a factory sample or a homemade one. Here The main advantages of industrial devices:

• Reliability.
• High performance.
• Quality assurance and availability of technical service.
• Security.

However, industrial designs have one significant drawback - a very high price. Not everyone can afford such units, so It is worth thinking about the advantages of homemade devices:

• Low price. Five times, and sometimes more, lower price compared to factory power generators.
• The simplicity of the device and a good knowledge of all the nodes of the apparatus, since everything was assembled by hand.
• The ability to upgrade and improve the technical data of the generator to suit your needs.

A do-it-yourself electric generator at home is unlikely to be of high performance, but it is quite capable of providing the minimum requirements. Another disadvantage of homemade products is electrical safety.

It is not always highly reliable, unlike industrial designs. Therefore, you should be very serious about choosing the type of generator. Not only saving money, but also the life, health of loved ones and oneself will depend on this decision.

Design and principle of operation

Electromagnetic induction underlies the operation of any generator that produces current. Anyone who remembers Faraday's law from the ninth grade physics course understands the principle of converting electromagnetic oscillations into a direct electric current. It is also obvious that creating favorable conditions for supplying sufficient voltage is not so simple.

Any electric generator consists of two main parts. They can have different modifications, but are present in any design:

There are two main types of generators, depending on the type of rotation of the rotor: asynchronous and synchronous. Choosing one of them, take into account the advantages and disadvantages of each. Most often, the choice of craftsmen falls on the first option. There are good reasons for this:

In connection with the above arguments, the most likely choice for self-manufacturing is an asynchronous generator. It remains only to find a suitable sample and a scheme for its manufacture.

Assembly order of the unit

First you need to equip the workplace with the necessary materials and tools. The workplace must comply with the safety regulations for working with electrical appliances. From the tools you will need everything related to electrical equipment and car maintenance. In fact, a well-equipped garage is quite suitable for creating your own generator. Here is what you need from the main details:

Having collected the necessary materials, they begin to calculate the future power of the apparatus. To do this, you need to perform three operations:

When the capacitors are soldered in place, and the desired voltage is obtained at the output, the structure is assembled.

In this case, the increased electrical hazard of such objects should be taken into account. It is important to consider proper grounding of the generator and carefully insulate all connections. Not only the service life of the device depends on the fulfillment of these requirements, but also the health of those who will use it.

car engine device

Using the scheme for assembling a device for generating current, many come up with their own incredible designs. For example, a bicycle or water-powered generator, a windmill. However, there is an option that does not require special design skills.

In any car engine there is an electric generator, which is most often quite serviceable, even if the engine itself has long been sent to the scrap. Therefore, having disassembled the engine, you can use the finished product for your own purposes.

Solving the problem with the rotation of the rotor is much easier than thinking about how to make it again. You can simply restore a broken engine and use it as a generator. To do this, all unnecessary components and devices are removed from the engine.

wind dynamo

In places where the winds blow without stopping, restless inventors are haunted by the waste of nature's energy. Many of them decide to create a small wind farm. To do this, you need to take the electric motor and convert it into a generator. The sequence of actions will be as follows:

Having made his own windmill with a small electric generator or a generator from a car engine with his own hands, the owner can be calm during unforeseen cataclysms: there will always be electric light in his house. Even after going out into nature, he will be able to continue to enjoy the convenience provided by electrical equipment.