induction generator. Alternating electric current. Alternating electric current generator. Alternating current alternator presentation

Definition Alternating current is an electric current that periodically changes in magnitude and direction. Symbol or. The module of the maximum value of the current strength for the period is called the amplitude of the current strength oscillations. Currently in electrical networks AC current is used. Many of the laws that were derived for direct current also apply to alternating current.

Alternating current has a number of advantages over direct current: - an alternating current generator is much simpler and cheaper than a direct current generator; - alternating current can be transformed; - alternating current is easily converted to direct current; - AC motors are much simpler and cheaper than DC motors; - the problem of power transmission over long distances was solved only by using high voltage alternating current and transformers. A sinusoidal voltage is used to produce alternating current.

An alternator is an electromechanical device that converts mechanical energy into AC electrical energy. Systems producing alternating current were known in simple types since the discovery of magnetic induction electric current. The principle of operation of the generator is based on the phenomenon of electromagnetic induction, the occurrence of electrical voltage in the stator winding, which is in an alternating magnetic field. It is created with the help of a rotating electromagnet of the rotor when a direct current passes through its winding.

"Alternator" Alternator (alternator)
is an electromechanical device,
which converts mechanical energy into
AC electrical energy.
Most alternators
using a rotating magnetic field.

Story:

General view of an alternator with internal poles. The rotor is an inductor and the stator is an armature

Generator device diagram: 1 - fixed armature, 2 - rotating inductor, 3 - contact rings, 4 - brushes sliding on them

Types of generators:

Wide application of alternators:

Electric current generator (old
name alternator) is
electromechanical device that
converts mechanical energy into
AC electrical energy.
Most alternators
using a rotating magnetic field.

Story:

All DC motors consist of a rotor and a stator, with the rotor being the moving part of the motor and the stator not.

Classification of generators by type of prime mover:

Turbogenerator

Diesel power plant (diesel generator)

hydro generator

wind generator

The use of generators in everyday life and at work

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Presentation on the topic: “Three-phase current generator” Municipal Atypical General Educational Institution “Gymnasium No. 1 of the city of Belovo” Head: Popova Irina Alexandrovna Completed by: students of class 11 “B” Ponomarev Kirill Malakhov Alexander Glushchenko Anatoly Belovo 2011 BRAIN 2.0

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Objectives: 1) understand the principle of operation of a three-phase generator 2) find out the advantages of three-phase systems 3) consider connections in three-phase circuits 4) compare phase (Uph) and linear (Ul) voltages 5) consider diagrams, graphs to study and consolidate knowledge of the topic. 6) do the experience, applying the knowledge gained 7) draw practical conclusions

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History of origin ... Mihai l O sipovich Dolivo-Dobrovolsky - Russian electrical engineer of Polish origin, one of the creators of three-phase alternating current technology, a German entrepreneur. The creative and engineering activities of M. O. Dolivo-Dobrovolsky were aimed at solving problems that would inevitably have to be faced with the widespread use of electricity. Work in this direction, based on the three-phase current obtained by Nikola Tesla, in an unusually short time led to the development of a three-phase electrical system and a perfect, in principle, design of an asynchronous electric motor that has not changed to date. Thus, currents with a phase difference of 120 degrees were obtained, a connected three-phase system was found, the distinctive feature of which was the use of only three wires for the transmission and distribution of electricity.

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The device of the three-phase current generator The principle of operation of the generator is based on the phenomenon of electromagnetic induction - the occurrence of electric voltage in the stator winding, which is in an alternating magnetic field. It is created with the help of a rotating electromagnet - a rotor when a direct current passes through its winding. Main elements: The inductor in the three-phase current generator is an electromagnet, the winding of which is powered by direct current. The inductor is the rotor, the generator armature is the stator. Three independent electric circuits are located in the stator slots. windings shifted in space by 120g. When the rotor rotates with an angular velocity, an EMF of induction occurs, changing. according to the harmonic law with a frequency ω Due to the shift of the windings in space, the phases of the oscillations are shifted by 2p/3 and 4p/3.

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Connections in three-phase circuits Phase voltage is the voltage between the beginning and end of each phase winding of the generator. Linear voltage is the voltage between the beginnings of any two phase windings.

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Experience Three coils with cores are placed in a circle at an angle of 120° with respect to each other. Each coil is connected to a galvanometer. A straight magnet is fixed on the axis in the center of the circle. If you rotate the magnet, then an alternating current appears in each of the three circuits. With a slow rotation of the magnet, it can be seen that the largest and smallest values ​​of the currents and their directions will be different at each moment in all three circuits.

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Advantages of three-phase systems: 1) cost-effectiveness of production and transmission of electricity 2) the possibility of obtaining a relatively simple circular rotation. magnetic field 3) the possibility of obtaining two operating voltages in one installation: phase and linear 4) the use of a smaller number of wires in production Conclusion: Due to these advantages, three-phase systems are the most common in modern electric power industry.

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List of used literature: Bessonov L.A. Theoretical foundations of electrical engineering: Electrical circuits. Proc. for students of electrical, energy and instrument-making specialties of universities. –7th ed., revised. and additional –M.: Higher. school, 1978. -528s.; Glazunov A.T., Kabardin O.F., Malinin A.N., Orlov V.A., Pinsky A.A., S.I. Kabardin "Physics. Grade 11". - M .: Education, 2009 Fundamentals of the theory of circuits: Proc. for universities /G.V.Zeveke, P.A.Ionkin, A.V.Netushil, S.V.Strakhov. –5th ed., revised. -M.: Energoatomizdat, 1989. -528s.

Regional State Autonomous Professional educational institution Borisov Agromechanical College

• Presentation for the lesson on the topic; The device and principle of operation of a car generator.

• according to MDK 01 02 "Device, maintenance
• and car repair

• Zdorovtsov Alexander Nikolaevich

• - a device that converts the mechanical energy received from the engine into electrical energy. Together with the voltage regulator, it is called a generator set. Alternators are installed on modern cars.

• the output parameters of the generator must be such that in any modes of vehicle movement there is no progressive discharge of the battery;
• the voltage in the car's on-board network, fed by the generator, must be stable over a wide range of changes in speed and loads.

• - serves to transfer mechanical energy from the engine to the generator shaft through a belt

• consists of two covers: front (from the side of the pulley) and rear (from the side of the slip rings), designed to mount the stator, install the generator on the engine and place the bearings (supports) of the rotor. On back cover a rectifier, brush assembly, voltage regulator (if built-in) and external leads for connection to the electrical system are placed;

• The rotor consists

• steel shaft with two beak-shaped steel bushings located on it. Between them there is an excitation winding, the conclusions of which are connected to slip rings. The generators are predominantly equipped with cylindrical copper slip rings;

• 1. rotor shaft; 2. rotor poles; 3. excitation winding; 4. slip rings.

• generator stator

• - a package made of steel sheets, having the shape of a pipe. In its grooves there is a three-phase winding, in which the power of the generator is generated;

• 1. stator winding; 2. winding conclusions; 3. magnetic core

• Assembly with rectifier diodes

• - combines six powerful diodes, pressed three into the positive and negative heat sinks;

• 1. power diodes; 2. additional diodes; 3. heat sink.

• - a device that maintains the voltage of the car's on-board network within the specified limits when changing electrical load, generator rotor speed and ambient temperature;

• – Removable plastic construction. It has spring-loaded brushes in contact with the rotor rings;

• Non-contact generator with excitation from permanent magnets.
• Beak-shaped alternator with slip rings
• Inductor alternator.

• a - generator model;
• · b-rotor with permanent magnet NS and with six claw-shaped poles;
• · in - a six-pole stator with three phase windings connected by a "star";
• · NS - cylindrical permanent magnet with N and S poles;
• M - stator magnetic circuit;
• · R- magnetic circuit of the rotor in the form of claw-shaped tips made of solid steel;
• · Ф - magnetic flux of the rotor;
• 8- air gap;
• F. - phase winding of the stator;
• · EF - EMF induced in the phase winding;
• · w - circular frequency of rotation of the rotor;
• 1. 2, 3, total - conclusions of the phase windings connected by a "star".

• the spinning rotor is a permanent magnet and the phase windings are coils on a fixed stator. Such a generator is called a non-contact permanent magnet excited alternator. It can be single phase or multidimensional. The generator is simple in design, reliable, not afraid of dirt, does not require electrical excitation, does not have rubbing electrical contacts, the service life is determined by the drying of the insulation of the phase windings. But on modern passenger cars, a generator with excitation from permanent magnets is not used due to the impossibility of strictly maintaining a constant operating voltage in it when changing the speed of the internal combustion engine.

• a - generator model; b - a dissected rotor with an excitation coil W„ and with six north N and six south S beak-shaped poles of a permanent electromagnet; c - simplified design of the generator;
• 1 - magnetic circuit M of the stator with phase windings Wph
• 2 - beak-shaped pole pieces of the rotor;
• 3 - excitation winding Wв;
• 4 - fan impeller;
• 5 - drive pulley;
• 6 - magnetic circuit R of the rotor;
• 7 - body covers;
• 8 - built-in rectifier;
• 9 - contact rings K;
• 10 - brush holder KShM with brushes.

• The winding Wb with its conclusions is connected to the contact rings K, which, in turn, are connected through the brushes of the KShM to the external electrical circuit arousal. In this way, the beak-shaped rotor becomes a multi-pole permanent electromagnet, the magnetomotive force of which can be easily adjusted by changing the excitation current, which is very important for automotive power generators.
• The beak-shaped rotor generator with slip rings has the widest application in modern passenger cars.

• a - generator model;
• b - connection diagram of the windings on a single-phase stator;
• c - simplified design of the generator;
• 1 - - groove of the rotor
• ;2 - bearing;
• 3 - rotor shaft;
• 4 - rotor pole
• ;5 - generator housing; Wv, Wf - excitation and phase windings.

• The main difference of this generator is that its rotating rotor is a passive magnetically soft ferromass, and the excitation winding is installed on a fixed stator together with phase windings. To reduce magnetic losses, the ferromass of the rotor, as well as the stator, is made of a set of thin plates of electrical steel. The generator is non-contact. The operation of such a generator is based on the periodic interruption of the constant magnetic flux, the stator, which, when the rotor rotates, is achieved by periodically changing the size of the air gap between the stator and the rotor. Thus, the inductor generator is synchronous and is controlled by voltage by changing the excitation current in the stator winding. In the inductor generator, the principle of obtaining EMF by changing the magnetic conductivity in the air gap is implemented: when controlling the magnitude of the induction of the stator magnetic field. By appropriate selection of the configuration of the surface of the passive rotor and stator pole pieces, it is possible to bring the periodicity of the change in the magnetic flux closer to the sinusoidal law, which provides a sinusoidal shape to the operating voltage of the generator.

• http://respektt.ru/foto/generator_ustroistvo.jpg
• http://www.mlab.org.ua/articles/electric/59-electric-generator.html
• http://www.domashniehitrosti.ru/generator4.html
• Rodichev V. A.: Trucks. M.: Publishing Center "Academy", 2010-239s.