Electric generator as it works. How does an induction generator of the rotational type

History

Systems producing alternating current were known in simple species from the opening times of the magnetic induction of the electric current. Early machines were developed by Pioneers as Michael Faraday and Ippolite Pixie.

Faraday developed a "rotating triangle", whose action was multipolar - Each active conductor was passed sequentially through the area where the magnetic field was in opposite directions. The first public demonstration of the strongest "alternator system" took place in 1886. Large two-phase generator alternating current British electrician James Edward Henry Gordon in 1882 was built. Lord Kelvin and Sebastian Ferranti also developed an early alternator that produced frequencies between 100 and 300 Hertz. In 1891, Nikola Tesla patented a practical "high-frequency" alternator (which acted at a frequency of about 15,000 hertz). After 1891, multiphase alternators were introduced.

The principle of the operation of the generator is based on the action of electromagnetic induction - the occurrence of electrical voltage in the winding of the stator in the alternating magnetic field. It is created using a rotating electromagnet - rotor when passing through its DC winding. A variable voltage is converted into a constant semiconductor rectifier.

Automotive generator

Car alternator. The drive belt is removed.

The AC generator is used on modern cars for charge batteries and for power supply to the automotive electrical system. In the AC generators, the switch is not used, it gives a great advantage over DC generators: they are easier, easier and cheaper. AC automotive generators use a set of rectifiers (diode bridge) to convert the AC to a constant current. For the production of DC with low ripples, automotive alternating current generators have three-phase winding and a three-phase rectifier.

Modern car alternating current generators have a voltage regulator built into them. Previously installed voltage regulators only analog view. At the moment, the relays regulators switched to digital Channel The so-called CAN bus.

Sea alternators

Marine alternators in yachts with appropriate adaptation to the salt and water environment.

Variable alternate current generators

The brushless generator consists of two generators on the same shaft. Small brushless generators may look like one unit, but two parts are easily identified on large generators. Most of the two are the main generator and the smaller is the causative agent. The causative agent has stationary field coils and rotating anchors (coil power). The main generator uses opposite configurations with a rotating field and stationary coils. The bridge rectifier (rotating rectifier) \u200b\u200bis mounted on the plate attached to the Rothor. Neither brushes nor contact rings are used, which reduces the number of wear parts.

Induction generator

Unlike the remaining generators, the operation of the induction generator is not a rotating magnetic field, but the pulsating, otherwise the field changes not in the movement function, but as a function of the time, which ultimately (EDC guidance) gives the same result.

The design of induction generators involves the placement and constant field and coils for the guidance of the EMF in the stator, the rotor remains free from the windings, but necessarily has a teeth, since all the operation of the generator is based on rotor's teeth harmonics.

Small Energy Generators

For power up to 100 kW, one and three-phase generators with permanent magnets were widely used. The use of high-energy constant magnets of the neodymium-iron-boron magnets made it possible to simplify the design and significantly reduce the size and weight of the generators, which is critical for low wind power.

AC generator design

In the most general case, the most commonly used three-phase alternator generator consists of an apparaced rotor with a single pair of poles (low-power engine generators) or 2 pairs of them, located crosswise (the most common generators of power up to several hundred kilowatt. This design not only allows you to more rationally use The material, but also for the industrial frequency of the AC 50 Hz gives the operating frequency of rotation of the rotor of 1500 revolutions per minute, which agrees well with the traction turnover of diesel engines of this power), as well as the stator with 3 (in the first case) or 6 (second) power Winding and poles. Voltage with power windings and there is something that is supplied to the consumer.

The rotor can be performed on permanent magnets only for very low-power generators, in all other cases it has winding so-called. The excitation windings, that is, it is an electromagnet of a direct current, powered in a rotating rotor through a brush-collective assembly with simple ring contacts, more resistant to wear than a split-side collector of DC machines.

In any powerful AC generator with a winding of excitation on the rotor, the question inevitably falls - what kind of excitation current is supplied to the coil? After all, it depends output voltage such a generator. And this voltage must be maintained at a certain framework, for example, 380 volts, regardless of current in the circuit of consumers, a significant amount of which is also capable of significantly reduce the output voltage of the generator. In addition, the load on the phases can generally be very uneven.

This issue is solved in modern generators, as a rule, in the output chains of the phases of the generator of electromagnetic transformers of the current connected by the secondary windings with a triangle or a star, and giving the alone's three-phase voltage to the output - dozens of volts, strictly proportional and agreed by phase loading current The generator is the larger current consumed at the current current, the greater the output voltage of the corresponding phase of the corresponding current transformer. This is achieved by a stabilizing and stepping effect. All three regulatory phases from secondary windings of current transformers are further reached on a conventional 3-phase rectifier of 6 semiconductor diodes, and at the output it turns out the constant current of the desired value, and the rotor excitation winding through the brush-collector node is obtained. The scheme can be supplemented with a roller node for some freedom of excitation current control.

In obsolete or low-power generators, instead of current transformers, a system of powerful retakes was used, with the exhaust of the operating current of the excitation by changing the voltage drop on the resistor when the current changes through it. These schemes were less accurate and much less economical.

In both cases, there is a problem of the initial voltage on the generator power windings at the time of the beginning of its work - indeed, if the excitation is not yet, then the current in the secondary windings of current transformers is nowhere to come. The problem, however, is solved by the fact that the iron of the Rotor Yarma has some ability to residual magnetization, this residual magnetization is sufficient to excite in the power windings of voltage into several volts sufficient for self-excitation of the generator and the output of it on operating characteristics.

In generators with self-excitation - a random supply of external voltage industrial is a serious danger. electrical network on the strength winding of the stator. Although this does not lead to some negative consequences for the generator windings themselves, a powerful alternating magnetic field from the external network effectively demagnetizes the stator, as a result of which the generator loses the ability to self-excitation. In this case, the initial excitation voltage supply from some external source, for example, car battery, Sometimes this procedure fully cures the stator, but in some cases the need to supply external arousal remains forever.

AC main generator

The main generator consists of a rotating magnetic field, as mentioned earlier, and fixed fittings (generator windings)

Hybrid cars

Links

Alternators. Integrated Publishing (Tpub.com).
Wooden Low-RPM Alternator. Forcefield, Fort Collins, Colorado, USA.

Induction alternator alternator. In induction alternating current generators, the mechanical energy turns into electrical. The induction generator consists of two parts: movable, called a rotor, and a fixed, which is called a stator. The generator action is based on the phenomenon of electromagnetic induction. Induction generators have a relatively simple device and allow you to obtain large currents at a fairly high voltage. Currently there are many types of induction generators, but they all consist of the same major parts. This is, first, an electromagnet or a permanent magnet that creates a magnetic field, and, secondly, a winding consisting of sequentially connected turns, in which a variable electromotive force is induced. Since the electromotive forces, induced in series connected turns, are folded, then the amplitude of the electromotive force of induction in the winding is proportional to the number of turns in it.

Fig. 6.9

The number of power lines penetrating each round is continuously changing from maximum valueWhen it is located across the field, to zero, when the power lines slide along the turn. As a result, when the turn is rotated between the magnet poles after each half-turn, the current direction changes to the opposite, and alternating current appears in the twist. In the external circuit, the current is given by sliding contacts. To do this, the contact rings attached to the ends of the winding are strengthened on the winding axis. Fixed plates - brushes are pressed to the rings and communicate with an external chain winding (Fig. 6.9).

Let the coil of the wire pumped in a single magnetic field with a constant angularity. Magnetic stream, piercing the coil, changes by law, here S. - Torch area. According to the law of Fepadiam in the winding, the electromotive force of induction is guided, which is assessed as follows:

where N. - The number of turns in the winding. Thus, the electromotive force of induction in the winding varies according to the sinusoidal law and the number of turns in the winding and the frequency of comprehension.

In the experiment with a rotating winding, the stator is a magnet and contacts, between which the winding is placed. In large industrial generators, an electromagnet rotates, which is a rotor, while the windings in which the electromotive force is presented, are laid in the stator grooves and remain fixed. On thermal power plants for rotation of the rotor, steam turbines are used. Turbines, in turn, are brought into rotation of water vapor jets obtained in huge steam boilers due to the burning of coal or gas (thermal power plants) or the decay of the substance (nuclear power plants). On hydroelectric power plants, water turbines are used to rotate rotor, which are rotated with water falling from a high height.

Electric generators play a crucial role in the development of our technological civilization, since they allow you to receive energy in one place, and use it in another. Steam machine, for example, can convert the coal combustion energy into a useful work, but it is possible to use this energy only where coal fire and a steam boiler are installed. The power plant can be accommodated very far from electricity consumers - and, nevertheless, supply plants, at home, etc.

They tell (most likely, this is just a beautiful fairy tale), as if Faradays demonstrated the prototype of the electric generator John Saw, the chancellor of the UK treasury, and he asked the scientist: "Well, Mr. Faraday, all this is very interesting, and which of all this is a lot?".

"What is fat? - Allegedly surprised Faraday. - Yes, you know, sir, how many taxes this thing will bring to the treasury over time?! "

Transformer.

Transformer. The electromotive force of powerful generators of power plants is large, meanwhile the practical use of electricity requires most often not very high voltages, and energy transfer, on the contrary, very high.

To reduce losses for heating wires, it is necessary to reduce the current strength in the transmission line, and, therefore, to save the power to increase the voltage. The voltage generated by the generators (usually about 20 kV) is raised to a voltage of 75 kV, 500 kV and even to a voltage of 1.15 mV, depending on the length of the power line. Raising voltage from 20 to 500 kV, that is, 25 times, reduce losses in line 625 times.

The transformation of an alternating current of a certain frequency at which the voltage increases or decreases several times with almost no power loss, is carried out by an electromagnetic device that does not have mobile parts - an electric transformer. Transformer is an important element of many electrical appliances and mechanisms. Charging device And the toy railways, radio and televisions - transformers that reduce or increase the voltage everywhere. Among them are found both completely tiny, no more peas and real colosses weighing hundreds of tons and more.

Fig. 6.10.

The transformer consists of a magnetic pipeline representing a set of plates that are usually made from ferromagnetic material (Fig. 6.10). On the magnetic conductory there are two windings - primary and secondary. The one of the windings that connects to the source of alternating voltage is called primary, and the one to which the "load" is attached, that is, the electricity consuming instruments are called secondary. The ferromagnet increases the amount of magnetic field strength lines of approximately 10,000 times and localizes the flow of magnetic induction within itself, due to which the transformer winding can be spatially separated and still remain inductively connected.

The transformer effect is based on mutual induction and self-induction phenomena. The induction between the primary and secondary winding is mutual, that is, the current flowing in the secondary winding induces the electromotive force in the primary, just as the primary winding induces the electromotive force in the secondary. Moreover, since the turns of the primary winding cover their own power lines, the electromotive power of self-induction occurs in them. The electromotive power of self-induction is also observed in the secondary winding.

Let the primary winding be connected to an AC source with an electromotive force, so it occurs an alternating current that creates a variable magnetic flow in the transformer magnetic circuit breed ? which focuses inside the magnetic core and permeates all the turns of the primary and secondary windings.

In the absence of an external nipper, the power is released into zero, that is, the current power is close to zero. Apply to the primary chain Ohm's law: the sum of the electromotive force of induction and voltage in the chain is equal to the product of the current for the resistance. Believing, you can write:, therefore, where F. - The flow permeating each turn of the primary coil. In the perfect transformer, all the power lines pass through all the turns of both windings, and since the changing magnetic field generates the same electromotive force in each turn, then the total electromotive force induced in the winding is proportional to the total number of its turns. Hence, .

The voltage transformation coefficient is equal to the ratio in the secondary chain to the voltage in the primary chain. For amplitude voltage values \u200b\u200bon windings, you can write:

Thus, the transformation coefficient is defined as the ratio of the number of turns of the secondary winding to the number of turns of the primary winding. If the coefficient, the transformer will increase, and if low.

The ratio written above, strictly speaking, applicable only to the perfect transformer, in which there is no scattering of the magnetic flux and there are no energy losses on Jowlelo heat. These losses can be associated with the presence of active resistance of the windings themselves and the occurrence of induction currents (Foucault currents) in the core.

Toki Foucault.

Toki Foucault. Induction currents can also occur in solid massive conductors. In this case, the closed induction current circuit is formed in the thickness of the conductor itself when it moves in a magnetic field or under the influence of an alternating magnetic field. These currents are named by the name of French physics Zh.B.L. Foucault, which in 1855 discovered the heating of ferromagnetic cores of electrical machines and other metal bodies in a variable magnetic field and explained this effect by exciting induction currents. These currents are currently called vortex currents or Fouco currents.

If the iron core is in a variable magnetic field, then in it under the action of the induction electric field there are internal vortex currents - Foucault currents leading to its heating. Since the electromotive force of induction is always proportional to the frequency of oscillations of the magnetic field, and the resistance of massive conductors is small, then at high frequency in the conductors will be highlighted, according to the law of Joule-Lenz, a large number of Heat.

In many cases, Foucault currents are undesirable, so you have to take special measures to reduce them. In particular, these currents cause heating ferromagnetic cores of transformers and metal parts of electrical machines. To reduce the losses of electrical energy due to the occurrence of vortex currents, the cores of transformers are made not from a solid piece of ferromagnet, but from separate metal plates, isolated from each other by the dielectric layer.

Fig. 6.11

The vortex currents are widely used for metal melting in the so-called induction furnaces (Fig. 6.11), for heating and melting metal blanks, obtaining particularly clean alloys and metals compounds. For this, the metal blank is placed in the induction furnace (the solenoid, which is passed by alternating current). Then, according to the law of electromagnetic induction, induction currents occur inside the metal, which warm the metal and can melt it. Creating a vacuum in the furnace and applying levitational heating (in this case, the power of the electromagnetic field is not only warming up the metal, but also hold it in a suspended state out of contact with the surface of the chamber), especially clean metals and alloys are obtained.

The generator is one of the main elements of the electrical equipment of the car, providing simultaneous meals for consumers and the rechargeable battery.

The principle of the device is built on the transformation of mechanical energy, which comes from the motor, into the voltage.

In the complex with the voltage regulator, the node is called the generator set.

Modern cars provide an AC unit fully satisfying all the claims.

Generator device

The elements of the AC source are hidden in one case, which is also the basis for the stator winding.

In the process of manufacturing the housing, light alloys are used (most often aluminum and durally), and for cooling there are holes that ensure timely heat dissipation from the winding.

In the front and rear of the casing, bearings are provided to which the rotor is attached - the main element of the power supply.

Almost all elements of the device are placed in the casing. In this case, the hull itself consists of two covers located on the left and on the right side - near the drive shaft and the control rings, respectively.

Two covers are combined with each other with special bolts made of aluminum alloy. This metal is characterized by a slight mass and ability to disperse heat.

An equally important role is played by a brush node that transmits the voltage to the contact rings and ensuring the operation of the node.

The product consists of a pair of graphite brushes, two springs and brush holder.

We also pay attention to the elements located inside the casing:

What requirements are presented to the car generator?

A number of requirements are put forward to the car generator set:

The voltage at the output of the device and, accordingly, in the onboard network should be maintained in a specific range, regardless of the load or the rotation frequency of the crankshaft.
Output parameters must have such indicators so that in any of the operation modes of the battery, a sufficient charge voltage was obtained.

At the same time, each car owner should pay special attention to the level and stability stability at the output. This requirement is caused by the fact that the battery is sensitive to similar changes.

For example, if the voltage is reduced below, the battery is not charged to the required level. As a result, problems are possible in the process of starting the motor.

In the inverse situation, when the installation issues an increased voltage, the battery recharges and breaks up faster.

Principle of operation of the automotive generator, features of the scheme

The principle of the generator node is built on the effect of electromagnetic induction.

In case of passing a magnetic flux through the coil and changes, the voltage appears on the outputs (depending on the rate of change of flow). Similarly, the reverse process is also working.

So, to produce a magnetic flux to be used to the coil voltage.

It turns out that two components are required to create alternating voltage:

The coil (it is from it that the tension is removed).
The source of the magnetic field.

An equally important element as noted above is the rotor acting as a source of a magnetic field.

The node's pole system has a residual magnetic flux (even in the absence of current in the winding).

This parameter is small, therefore it is able to cause self-excitation only on high revs. For this reason, a small current is passed on the rotor winding, providing magnetization of the device.

The chain mentioned above implies the passage of the current from the battery through the control light bulb.

The main parameter here is the strength of the current that is within the normal range. If the current is overpriced, the battery will quickly discharge, and if the risk of excitation of the generator on the XX motor (idle) will increase.

Taking into account these parameters, the power of the light bulb is also selected, which should be 2-3 W.

As soon as the voltage reaches the desired parameter, the light bulb goes out, and the excitation windings are powered by the automotive generator. In this case, the power source goes into self-excitation mode.

The removal of the voltage is made from the stator winding, which is made in three-phase design.

The node consists of 3-individual (phase) windings wound on a certain principle on the magnetic lines.

Current and voltages in the windings are shifted by 120 degrees. At the same time, the windings themselves can be collected in two versions - "star" or "triangle".

If the "Triangle" scheme is selected, phase currents in 3 windings will be 1.73 times less than the total current given by the generator set.

That is why in automotive high power generators, the triangle scheme is most often used.

This is just due to lower currents, thanks to which it is possible to wind the winding of a smaller cross section.

The same wire can be used in the "Star" type connections.

In order for the generated magnetic stream to go to the destination, and went to the stator winding, the coils are in special grooves of the magnetic pipeline.

Due to the appearance of a magnetic field in windings and in a stator magnetic circuit, vortex currents appear.

The latter's action leads to the heating of the stator and reduce the power of the generator. To reduce this effect in the manufacture of the magnetic pipeline, steel plates are used.

The developed voltage enters the on-board network through a group of diodes (rectifier bridge), which was mentioned above.

After opening, the diodes do not create resistance, and give the current to be easily passing into the on-board network.

But at reverse voltage I is not skipped. In fact, only positive half-wave remains.

Some car manufacturers for protecting electronics change diodes to Stabilians.

The main feature of the details is the ability to not pass the current to a certain voltage parameter (25-30 volts).

After the passage of this limit, the stabilitron "breaks through" and passes the reverse current. At the same time, the voltage on the "plus" wire of the generator remains unchanged, which is not risks for the device.

By the way, the ability of Stabilon to maintain constant U on the outputs even after the "breakdown" is used in the regulators.

As a result, after passing a diode bridge (stabilion), the voltage is straightened, becomes constant.

Many types of generator sets, the excitation winding has its own rectifier collected from 3 diodes.

Thanks to this connection, the flow of discharge current from the battery is excluded.

Diodes related to the coating winding work on a similar principle and feed the winding of a constant voltage.

Here, the rectifier device consists of six diodes, three of which are negative.

During the operation of the excitation current generator below the parameter that gives a car generator.

Therefore, to straighten the current on the excitation winding of sufficient diodes with a rated current of up to two amps.

For comparison, power rectifiers have a rated current of up to 20-25 amps. If you want to increase the power of the generator, another shoulder with diodes is set.

Modes of work

To understand the features of the operation of the automotive generator, it is important to understand the features of each of the modes:

In the process of starting the engine, the main consumer of electrical energy is the starter. The peculiarity of the mode is to create an increased load, which leads to a decrease in the voltage at the ACB output. As a result, consumers take a current only from the battery. That is why in this mode the battery is discharged with the greatest activity.
After the engine factory, the car generator switches to the power source mode. From this point on, the device gives a current that is needed to power the load in the car and the recharge of the AKB. As soon as the battery dials the required capacity, the charging current level is reduced. At the same time, the generator continues to play the role of the main power source.
After connecting the powerful load, for example, air conditioning, the heating of the cabin and others, the rotor speed slows down. In this case, the car generator is no longer capable of covering the needs of the car in the current. Part of the load is shifted on the battery, which works in a parallel with a power source and begins to gradually discharge.

Voltage Regulator - Functions, Types, Control Lamp

The key element of the generator set is the voltage regulator - a device that supports the safe level U at the output of the stator.

Such products are two types:

Hybrid - regulators, electrical circuit which includes both electronic devices and radio components.
Integral - devices based on thin-film microelectronic technology. In modern cars, this option was the greatest distribution.

An equally important element is a control lamp mounted on the dashboard, which can be concluded about the presence of problems with the regulator.

Ignition of the light bulb at the time of starting the motor should be short-lived. If it burns constantly (when the generator installation in operation), this indicates a breakdown of the regulator or the node itself, as well as the need for repair.

Subtleties of fastening

The fixation of the generator installation is performed using a special bracket and bolted compound.

The node itself is attached to the front of the engine, thanks to special paws and prunes.

If special paws are provided on the automobile generator, the latter are on the lids of the motor.

In the case of applying only one locking paw, the latter is placed only on the front lid.

In the paw installed in the rear, as a rule, a hole with a remote sleeve installed in it is provided.

The task of the latter is to eliminate the gap created between the focus and fastening.

Fastening the Audi A8 generator.

And so the unit is attached to the VAZ 21124.

Malfunctions of the generator and ways to eliminate them

The electrical equipment of the car has a bodging property. At the same time, the greatest problems arise with the battery and the generator.

In case of failure of any of these elements, the operation of the vehicle in the normal mode of operation becomes impossible or the car turns out to be completely immobilized.

All breakdowns of the generator are conventionally divided into two categories:

Mechanical. In this case, the problems arise the integrity of the hull, springs, belt drive and other elements that are not associated with the electrical component.
Electric. This includes a diode bridge malfunction, brushes wear, closure in windings, breakdowns of the regulator relay and others.

Now consider a list of faults and symptoms in more detail.

1. At the output, a lack of charging current level:

2. Second situation.

When the car generator gives the necessary level of current, but the battery is still not charging.

Causes can be different:

Low quality of the "Mass" contact broach between the regulator and the main node. In this case, check the quality of the contact connection.
The failure failure failure relay - check and change it.
Covered or brushes hung - replace or clean from dirt.
Worked the protective relay of the regulator due to the presence of a closure on the "mass". The solution is to find the place of damage and remove the problem.
Other reasons are the combination of contacts, breakdown of the voltage controller, the viton closure in the stator windings, poor belt tension.

3. The generator works, but makes elevated noise.

Probable faults:

Circuit between the vitches of the stator.
Wear room for landing bearing.
Remove the pulley nut.
Bearing destruction.

The repair of the car generator should always begin with accurate diagnosis of the problem, after which the cause is eliminated by preventive measures or replacing the failed node.

Operating practice shows that it is easy to change the car generator, but a number of rules are required to solve the problem:

A new device must have similar current-speed parameters, like the factory node.
Energy indicators must be identical.
The gear ratios at the old and new power source must coincide.
The installed node must be approached in size and easily attached to the motor.
The schemes of the new and old automotive generator should be the same.

Note that the devices mounted on foreign cars are recorded not as domestic, for example, as on the Toyota Corolla generator
And Lada Granta
.

Consequently, if you change the foreign unit with a product of domestic production, you will have to install a new mount.

At the end of the story about automotive generators, it is worth highlighting a number of tips, which is necessary, and which cannot be done by car owners during operation.

The main point is the installation, in the process of which it is important to approach polarity with utter attention.

If you make a mistake in this matter, the rectifier device breaks and increases the risk of fire.

A similar danger also carries the engine start with incorrectly connected wires.

To avoid problems during operation, it is worth sticking to a number of rules:

Follow the cleanliness of the contacts and monitor the repair of the car's electrical wiring. Separate attention to complete the reliability of the connection. In the case of using bad contact wires, the level of the on-board voltage will be released for the allowable limit.
Follow the tension of the generator. In case of weak tension, the power source will not be able to perform the tasks. If you drag the belt, it is fraught with rapid wear of bearings.
Return the wires from the generator and the battery when performing electric welding work.
If the check light lights up and continues to burn after starting the motor, find out and eliminate the cause.

Separate attention should be paid to the relay controller, as well as check the voltage at the output of the power supply. In charge mode, this parameter must be at the level of 13.9-14.5 volts.

In addition, from time to time check the wear and sufficiency of the generator brushes, the condition of bearings and contact rings.

The height of the brushes should be measured at a dismantled holder. If the latter caught up to 8-10 mm, replacement is required.

As for the efforts of springs, holding brushes, it should be at 4.2 N (for VAZ). In this case, look at the contact rings - they should not be traces of oil.

Also, the car owner must also remember a number of prohibitions, namely:

Do not leave the machine with a connected battery if there are suspicions of the diode bridge breakage. Otherwise, the battery will quickly discharge, and the risk of inflammation of the wiring is increasing.
Do not check the correct operation of the generator by leaving its conclusions or disabling the ACB when the engine is running. In this case, there is a breakdown of electronic elements, on-board computer or voltage regulator.
Do not allow technical fluids to enter the generator.
Do not leave the node included if the battery terminals were removed. Otherwise, this can lead to a breakdown of the voltage regulator and electrical equipment.
Conduct in a timely manner.

Knowing the features of the operation of the generator, the nuances of its design, the main malfunctions and subtleties of repair, can avoid many problems with wiring and battery.

Remember that the generator is a complex node requiring a special approach to operation.

It is important to constantly monitor him, timely conduct preventive measures and the replacement of parts (if there is such a need).

With this approach, the power source and the car itself will serve for a very long time.

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Alternating current is the driving force of many industries and transport, in particular, cars. There are both small models of the magnitude with fist and giant devices several meters in height.

The generator is the same technical systemwhich transforms mechanical (kinetic) energy into electrical. How does the generator act?

No matter how the generator was not arranged, the process is based on its action electromagnetic induction - The appearance in the closed circuit of the electric current under the influence of a modified magnetic flux.

The generator is conditionally divided into 2 parts: inductor and anchor.

The inductor is called the part of the device where the magnetic field is created, and the anchor is the one half, where the electromotive force or current is formed.

Permanent remains its technical structure: wire winding and magnet.

The winding occurs an electromotive force under the influence of a magnetic field. This is the basis for the generator. But a powerful alternating current cannot be obtained from such a primitive design. For conversion, a strong magnetic flux is needed.

To do this, 2 steel cores are added to the wire winding, which determine the purpose and device of the alternator of the AC. This is a stator and rotor. A winding that creates a magnetic field is placed in the groove of one core - this is a stator, or inductor. It remains still unlike the rotor. The stator is powered by a constant current. There are bipoly or multipole.

The rotor, or also an anchor, actively rotates with the help of bearings and produces an electromotive force or alternating current. It is an internal core with copper wire winding.

The generator has a durable metal case with multiple outputs, which depends on the target device. Change the number of coils with wire winding.

We understand the features of the functioning of the aggregate

Now find out what principle the operation of alternating current generators is based. The functioning scheme is quite simple and understandable. Under the condition of constant rotor speed, the electric current will be carried out by a single thread.

Rotation of the rotor provokes a change in the magnetic flux. In turn, the electric field generates the appearance of an electric current. Through contacts with rings at the end of the current from the rotor passes into the electrical circuit of the device. Rings have a good sliding property. They are firmly in contact with brushes, which are constant stationary conductors between electrical chain and copper wire winding of the rotor.

In the copper winding around the magnet there is a current, but it is very weak in comparison with the power of electric current, which comes out of the rotor on the chain into the device.

For this reason, only a weak current is used to rotate the rotor, which was supplied by sliding contacts.

When assembling an AC generator, it is very important to withstand the proportions of the parts, the size, the values \u200b\u200bof the gaps, the thickness of the wire veins.
You can collect an AC generator if you have all the necessary parts and a sufficient amount of copper wire. Make a small unit is quite real. Or for use there is a detailed instruction.

Device and the principle of operation of the alternator of the AC on video

The term "generation" in electrical engineering came from Latin. He denotes "Birth". In relation to the energy, we can say that the generators are called technical devicesengaged in the production of electricity.

In this case, it is necessary to make a reservation that it is possible to produce an electric current by converting various types of energy, for example:

chemical;

light;

thermal and others.

Historically, it was found that the generators call structures that convert the kinetic energy of rotation into electricity.

By type of electricity produced, generators are:

1. DC;

2. A variable.

Physical laws that allow you to create modern electrical installations to generate electricity due to transformations of mechanical energy, open by scientists Ersteted and Faraday.

In the design of any generator, it is implemented when an electric current is placed in a closed frame due to the intersection of it with a rotating magnetic field, which is created in simplified household models or excitation windings on industrial products of elevated capacities.

When the frame is rotated, the magnetic flux value changes.

The electromotive force induced in the twist depends on the rate of change of the magnetic flux, which pierces the frame in the closed circuit S, and is directly proportional to its value. The faster the rotor is rotated, the higher the magnitude of the produced voltage.

In order to create a closed loop and remove the electric current from it, it was necessary to create a collector and a brush node that provides permanent contact between the rotating frame and stationaryly located part of the circuit.

Due to the design of spring-loaded brushes, pressed against the collector plates, the electric current is transmitted to the output terminals, and then it enters the network of the consumer.

Principle of operation of the simplest DC generator

When the frame is rotated around the axis, its left and right halves cyclically pass around the southern or north pole of magnets. In them, each time the current directions are changed to the opposite so that each poles they flow in one direction.

In order for a permanent current in the output circuit, a semiring unit was created on the collector node for each halve of the winding. The brushes adjacent to the ring remove the potential of only its sign: positive or negative.

Since the semiring of the rotating frame is open, then it creates moments when the current reaches the maximum value or missing. To maintain not only the direction, but also the constant value of the produced voltage, the frame is manufactured by specially prepared technology:

it uses not one round, but several - depending on the magnitude of the planned voltage;

the number of the framework is not limited to one instance: they are trying to make sufficient quantities to optimally maintain voltage drops at one level.

The constant current generator, the rotor winding is placed in the grooves. This makes it possible to reduce the loss of the indoor electromagnetic field.

Constructive features of DC generators

The main elements of the device are:

external power frame;

magnetic poles;

stator;

rotating rotor;

switching knot with brushes.

The housing is made of steel alloys or cast iron to give the mechanical strength of the overall structure. An additional challenge is the transmission of a magnetic flux between poles.

The poles of magnets are attached to the body with pins or bolts. Mounted winding.

The stator, called another Yarma or core, is made of ferromagnetic materials. It places winding coil of excitation. Stator core Equipped with magnetic poles forming its magnetic power field.

The rotor has synonym: anchor. Its magnetic circuit consists of chosen plates that reduce the formation of vortex currents and increase efficiency. In the core grooves laid rotor and / or self-excitation windings.

Switching knot With brushes can have a different number of poles, but it is always multiple two. Brushes material usually use graphite. The collector plates are made of copper as the most optimal metal suitable for the electrical properties of current conductivity.

Through the use of the switch on the output terminals of the DC generator, a pulsating type is formed.

Main types of DC generators designs

By type of power, the excitation winding distinguish devices:

1. With self-excitation;

2. Working on the basis of independent inclusion.

The first products can:

use permanent magnets;

or work from external sources, for example, rechargeable batteries, wind installation ...

An independent enable generators work from their own winding, which can be connected:

sequentially;

shunts or parallel excitation.

One of the variants of such a connection is shown in the diagram.

An example of a DC generator can serve as a design that used to be used before the automotive technique. Its device is the same as the asynchronous engine.

Such collector designs are capable of working in engine or generator mode simultaneously. Due to this, they were distributed in existing hybrid cars.

The process of forming an anchor reaction

It occurs in idle mode when incorrect setting Efforts of pressing brushes creating non-optimal regime Their friction. This can lead to a decrease in magnetic fields or the emergence of a fire due to increased education of sparks.

Ways to reduce it are:

compensation of magnetic fields due to the connection of additional poles;

setting the position of collector brushes.

Advantages of DC generators

These include:

lack of losses for hysteresis and the formation of vortex currents;

work in extreme conditions;

low weight and small dimensions.

Principle of operation of the simplest alternator

Inside this design, all the same details are used as the previous analogue:

a magnetic field;

rotating frame;

collector knot with brushes for current removal.

The main difference lies in the device of the collector node, which is created so that when the frame is rotated through the brushes, contact with its half frame is constantly created without cyclical change of their position.

Due to this current, replacing under the laws of harmonics in each half, completely unchanged is transmitted to the brushes and then through them into the consumer scheme.

Naturally, the frame is created by winding not from one turn, but calculated by their quantity to achieve optimal voltage.

Thus, the principle of operation of permanent and alternating current generators is general, and the differences in the design are made:

collector node rotating rotor;

configuration windings on the rotor.

Design features of industrial alternators of alternating current

Consider the main parts of the industrial induction generator, in which the rotor receives a rotational movement from a nearby turbine. The stator design includes an electromagnet (although the magnetic field can be created by a set of permanent magnets) and the rotor winding with a certain number of turns.

Inside each turn, an electromotive force is induced, which consistently folds in each of them and forms on the output clamps the total voltage value issued on the power scheme of the connected consumers.

To increase the emission amplitude at the outlet of the generator, use the special design of the magnetic system, made of two magnetic cores due to the use of special varieties of electrical steel in the form of elevated plates with grooves. The windings are mounted inside them.

The generator casing is a stator core with grooves for placing a winding that creates a magnetic field.

Rotating on the bearings, the rotor also has a magnetic circuit with the grooves, inside which the winding is mounted that receives an induced EMF. Usually, a horizontal direction is selected to accommodate the rotation axis, although there are designs of generators with a vertical arrangement and the corresponding structures design.

Between the stator and the rotor always creates a gap required to ensure the rotation and exclusion of the jam. But at the same time there is a loss of magnetic induction energy. Therefore, he is trying to make the minimum possible, optimally considering both of these requirements.

Located on a single shaft with the rotor, the pathogen is an electrical generator of a direct current, which has a relatively small power. Its appointment: to feed the electricity winding of the power generator in the state of independent excitation.

Such pathogens are used most often with the structures of turbine or hydraulic electrical generators when creating the main or backup excitation method.

The image of the industrial generator shows the location of the collector rings and brushes for removing currents from the design of the rotating rotor. This node under work is experiencing constant mechanical and electrical loads. To overcome them, a complex design is created, which during operation requires periodic inspections and implementation of preventive measures.

To reduce the operating costs created, the other, alternative technology, at which the interaction between rotating electromagnetic fields is also used. Only on the rotor there are permanent or electric magnets, and the voltage is removed from the stationaryly located winding.

When creating a similar scheme, such a design can be called the term "alternator". It is used in synchronous generators: high-frequency, automotive, locomotive and vessels, installations of electric power plants for electricity production.

Features of synchronous generators

Operating principle

The name and distinguishing feature of the action is concluded in the creation of a rigid connection between the frequency of the variable of the electromotive force, are injected in the stator winding "F" and rotation of the rotor.

A three-phase winding is built in the stator, and on the rotor - electromagnet with a core and an excitation winding, powered by DC circuits through a brush collector node.

The rotor is driven by the source of mechanical energy - the drive motor at the same speed. His magnetic field makes the same movement.

The stator windings are subject to the same largest, but shifted by 120 degrees in the direction of electromotive forces, creating a three-phase symmetric system.

When connected to the ends of the circuits of consumers, the currents of the phases begin to operate, which form the magnetic field, rotating in the same way: synchronously.

The form of the output signal inhibited EMF depends only on the law of the distribution of the magnetic induction vector inside the gap between the poles of the rotor and the stator plates. Therefore, it seeks the creation of such a design when the induction value changes according to the sinusoidal law.

When the gap has a constant characteristic, the magnetic induction vector inside the gap is created in the form of a trapezoid, as shown on the graph of the lines 1.

If the shape of the edges on the poles is fixed to the row angular with a change in the gap to the maximum value, then the sinusoidal distribution form can be achieved, as shown by the line 2. This technique and enjoy in practice.

Schemes for excitation of synchronous generators

Magnethodific force arising on the winding of the excitation of the "s" rotor creates its magnetic field. For this, there are different designs of DC pathogens based on:

1. Contact method;

2. Contactless way.

In the first case, a separate generator is used, called the causative agent "B". Its excitation winding is powered by an additional generator on the principle of parallel excitation, called the "PV" trivial.

All rotors are placed on the general shaft. Due to this, they rotate completely equally. Reostates R1 and R2 are used to regulate currents in the pathogen and proportel schemes.

With a non-contact method There are no contact rings of the rotor. Directly on it is mounted a three-phase winding of the pathogen. It is synchronously rotated with the rotor and transmits an electric direct current through a rotating rectifier directly to the winding of the causative agent "B".

The varieties of contactless scheme are:

1. System of self-excitation from its own stator winding;

2. Automated diagram.

At the first method The stator voltage of the stator enters a downstream transformer, and then the semiconductor rectifier "PP", which generates a constant current.

In this method, initial arousal is created due to the phenomenon of residual magnetism.

Automatic self-excitation creation scheme includes use:

voltage transformer TN;

automated ABR excitation regulator;

current transformer TT;

rectifying transformer W;

thyristor converter TP;

block protection BZ.

Features of asynchronous generators

The fundamental difference between these structures is the absence of a rigid connection between the rotor rotation frequencies (Nr) and induced in the winding of EMF (N). There is always a difference between them, which is called "sliding". It is denoted by the Latin letter "S" and express the formula s \u003d (n-nr) / n.

When the load is connected, the generator creates a braking torque for rotation of the rotor. It affects the frequency of EDC generated, creates a negative slip.

The design of the rotor in asynchronous generators is manufactured:

short-circuited;

phase;

hollow.

Asynchronous generators may have:

1. Independent excitation;

2. Self-excitation.

In the first case used external source AC voltage, and in the second - semiconductor transducers or condensers in the primary, secondary or both types of schemes.

Thus, alternate and direct current generators have many general features in the principles of construction, but differ in the constructive performance of certain elements.