RU2752527C1 - Synchronous generator apparatus with excitation from permanent magnets - Google Patents

Abstract

FIELD: electrical engineering.SUBSTANCE: invention relates to electrical engineering and can be used in creation and operation of brushless synchronous generators with permanent magnets, in particular, for power supply of rolling stock wagons, as well as for autonomous power supply of various objects. A rotor with tangential magnetisation is used in the proposed synchronous generator apparatus with excitation from permanent magnets, making it possible to use light non-magnetic materials, such as titanium, aluminium etc., for manufacture thereof, thereby significantly reducing the weight of the generator, to significantly increase working inductions in the air gap (almost double) from inductions of permanent magnets. The distribution of the stator windings in the grooves over the surface of the stator allows for more efficient use of the magnetic flux created by the permanent magnets of the rotor.EFFECT: increasing the specific power and performance coefficient, efficiency of operation of the generator by increasing working inductions in the air gap and providing a low initial speed, high reliability and active operation life of the generator.1 cl, 3 dwg, 1 tbl

Description

Appointment

The invention relates to the electrical industry and can be used in the creation and operation of brushless synchronous generators with permanent magnets, in particular for power supply of rolling stock cars, as well as autonomous power supply of various objects.

State of the art

It is known (see RF patent, No. 2 334 348) that the source of power supply with a capacity of more than 30 kVA for a rolling stock car on railway transport during its movement is an undercar generator of three-phase alternating current voltage 380 V with a drive for rotating its rotor from the axis of the car wheelset.

So, the 2GV.13 U1 undercar generator used today for these purposes is an inductor, two-pack, three-phase, reversible (see website: https://studfiles.net/preview/4021502/page:6/) provides a power of 34 kVA and has weight 700 kg.

In this generator, kinetic energy of rotation is generated from the axis of the wheelset of the rolling car, this rotation is transmitted to the rotor of the generator mounted on bearings in the steel case of the generator containing a stacked package of stator sheets, in the grooves of which three-phase multi-pole windings are laid, the excitation winding is installed between the stators, lead wires stator windings and field windings are output to the terminal box, the generated three-phase voltages of the generator are converted into the required charging current and fed to the battery for charging it, while the generated three-phase voltages of the generator and the constant voltage of the battery are converted into specified constant and alternating voltages and supplied to consumers electricity.

The disadvantage of this generator is its low power density (the ratio of the electric power generated by the generator to its mass is approximately 49 W / kg) and the operating efficiency due to the fact that a high initial speed of the carriage is required, at which the generator generates a voltage sufficient to start charging the battery (initial speed of the car V _nach = 30-35 km / h) and low efficiency. A rolling car has a limited undercarriage volumetric space, so the power density is the most important indicator.

Closest to the proposed invention is a brushless synchronous generator with permanent magnets (RF patent, No. 2 303 849), taken by the authors as a prototype.

A prototype consists of one or more sections, each of which includes:

• a rotor with a circular magnetic circuit, on which an even number of permanent magnets is fixed with the same pitch;

• a stator carrying an even number of horseshoe-shaped (U-shaped) electromagnets, located in pairs opposite each other and having two coils with sequentially opposite winding direction.

Permanent magnets are attached to the magnetic circuit in such a way that they form two parallel rows of poles with longitudinally and transversely alternating polarity. The electromagnets are oriented across the named rows of poles so that each of the coils of the electromagnet is positioned above one of the parallel rows of rotor poles. The number of poles in one row, equal to n, satisfies the relation: n = 10 + 4k, where k is an integer taking the values 0, 1, 2, 3, etc. Depending on the features of the generator's operation, the rotor can be located both on the outside of the stator and inside the stator.

An electric generator can include several identical sections. The number of such sections depends on the power of the mechanical energy source (drive) and the required parameters of the generator. It is preferable that the sections are out of phase with respect to each other. This can be achieved, for example, by the initial displacement of the rotor in adjacent sections by an angle α lying in the range from 0 ° to 360 ° / n; or by angular displacement of the stator electromagnets in adjacent sections relative to each other. To generate the required voltages for power supply to the consumer, a voltage regulator unit is connected to the output terminals of the generator. The principle of operation of an electric generator is similar to that of a traditional synchronous generator. The rotor shaft is mechanically connected to the drive (source of mechanical energy). Under the action of the drive torque, the generator rotor rotates at a certain frequency. In this case, EMF is induced in the winding of the coils of electromagnets in accordance with the phenomenon of electromagnetic induction. Since the coils of an individual electromagnet have a different winding direction and are at any time in the range of different magnetic poles, the induced EMF in each of the windings is added.

In the process of rotation of the rotor, the magnetic field of the permanent magnet rotates at a certain frequency, therefore, each of the windings of the electromagnets alternately turns out to be in the zone of the north (N) magnetic pole, then in the zone of the south (S) magnetic pole. In this case, the change of poles is accompanied by a change in the direction of the EMF in the windings of the electromagnets.

In contrast to the above 2GV.13 U1 undercar generator, the prototype does not have an excitation winding between the stators, which allows for higher power density and efficiency, as well as higher operating efficiency.

However, the generator uses a rotor with a circular magnetic circuit (magnetic iron) and radial magnetization (see DA Booth. Contactless electrical machines. M .: "High school", 1985. pp. 62-63), which leads to the following disadvantages:

• for a generator of high power (the required power of the undercar generator is more than 30 kVA), the magnetic iron has a large mass, which negatively affects the specific power of the generator;

• pole pieces are required, in the form of additional (damping) windings, which leads to an additional increase in the mass of the generator and to the complication of its design;

• the stator windings are locally concentrated on the poles, which does not allow efficient use of the magnetic flux of permanent magnets.

The aim of the present invention is to increase the power density and efficiency of a synchronous generator with permanent magnet excitation.

Disclosure of invention

A permanent magnet synchronous generator device includes a generator body; a rotor with permanent magnets of an even number fixed on it, mounted on bearings in the generator housing and mechanically connected to the drive from the axle of the wheelset of the moving car; a stator, the windings of which are connected by lead wires to a terminal box connected to the voltage regulator unit, while there is an air gap between the rotor and the stator.

The rotor is a tangential magnetization rotor with holes for cooling and is made in the form of a set of discs made of non-magnetic material, while permanent magnets are installed in the rotor windows with counter-magnetization relative to each radial of the pair, between these pairs in other windows there are poles made of ferromagnetic iron with holes for their fastenings, and the stator windings are distributed along the slots on the surface of the stator with holes for its cooling.

The essence of the invention lies in the fact that the generator uses a rotor with tangential magnetization (see DA Booth. Contactless electrical machines. M .: "High school", 1985. Page 63), which allows:

• use for its manufacture light non-magnetic materials, such as titanium, aluminum, etc., and thereby significantly reduce the weight of the generator;

• significantly increase the working induction in the air gap (almost twice) from the induction of permanent magnets.

In addition, the distribution of the stator windings in the slots over the stator surface allows more efficient use of the magnetic flux generated by the permanent magnets of the rotor.

Graphic illustrations:

• FIG. 1 - generator device with excitation from permanent magnets (front view from the drive side);

• FIG. 2 - generator device with excitation from permanent magnets (side view);

• FIG. 3 - rotor disk device.

Implementation of the invention

The permanent magnet generator device comprises components indicated by the reference numerals in FIG. 1, fig. 2, fig. 3:

1 - permanent magnets;

2 - generator case;

3 - windings (stator);

4 - stator;

5 - rotor;

6 - air gap;

7 - poles (ferromagnetic iron);

8 - holes for fastening poles;

9 - shaft;

10 - key for fastening the rotor to the shaft;

11 - bearing unit cover;

12 - bearing shield;

13 - bolts for fastening the bearing unit cover to the bearing shield;

14 - bolts for fastening the bearing shields to the generator case;

15 - fastening bolt for connecting the rotor to the drive;

16 - holes for stator cooling;

17 - holes for cooling the rotor;

18 - bearings;

19 - terminal box;

20 - drive (from the axis of the wheelset of the rolling car);

21 - voltage regulator unit;

22 - rotor disk;

23 - window (for permanent magnets);

24 - window (for poles);

25 - keyway.

The device of a synchronous generator with excitation from permanent magnets includes a generator body 2, a rotor 5 with an even number of permanent magnets 1 attached to it, mounted on bearings 18 in the generator body 2 and mechanically connected to the drive 20 from the axis of the wheelset of the rolling car, stator 4 , the windings 3 of which are connected by lead wires to the terminal box 19 connected to the voltage regulator unit 21, while there is an air gap 6 between the rotor 5 and the stator 4.

The rotor 5 is a tangential magnetization rotor with holes for cooling 17, made of a set of discs 22 made of non-magnetic material. In the windows 23 (for permanent magnets) of the rotor 5, permanent magnets 1 are installed with counter-magnetization relative to each adjacent pair. Between these pairs in the windows 24 (for the poles) there are poles 7 made of ferromagnetic iron with holes 8 for fastening them. The stator windings 3 are distributed in slots on the surface of the stator 4 with holes 16 for its cooling. The fastening bolt 15 connects the rotor 5 to the drive 20 from the axis of the wheelset of the rolling car. The rotor 5 is fixed to the shaft 9 by means of a key 10 installed in the groove 25. The bearings 18 are mounted on the shield 12, which are closed by the cover 11, which is attached to the shield 12 with bolts 13. The shield 12 is attached to the generator body 2 with bolts 14. Between the rotor 5 and the stator 4 has a working air gap 6.

Description of the operation of the generator device with permanent magnet excitation

In the initial state, when the car is stationary, there is no kinetic energy of rotation from the axis of the wheelset of the car, which ensures the rotation of the rotor 5 through the drive 20. There is no signal on the output wires of the stator windings 3 connected to the terminal box 19 (at the generator output). At the beginning of the movement of the car, due to the rotation of the axis of its wheelset, the rotor 5 comes into rotation through the drive 20, the poles of which induce an electromotive force in the three-phase multi-pole windings of the stator 4, which has holes for cooling 16, and connected by a star (see site: https: //forum220.ru/winding-connection-generators.php). At the output of the generator (in terminal box 19), upon reaching a certain initial speed of rotation of the rotor 5, a three-phase voltage appears.

As a drive for the axle of a wheelset of a mobile car 20, you can use, for example, a drive with a gearbox VBA-32/2 (see Fig.8.8 on the website: http://scbist.com/wiki/13666-privody-podvagonnyh-generatorov.html ), which transmits the rotational moment of the axle of the wheelset to the shaft 9 of the rotor 5, mounted on bearings 19.

The alternating three-phase voltage generated at the generator output enters the voltage regulator unit 21 (see patent, RF, No. 2 334 348), which generates the specified constant and alternating voltages for electricity consumers in the car.

It should be noted that in the proposed generator device with excitation from permanent magnets, there are no excitation windings that stabilize the output voltages within certain limits by smoothly changing the current in the excitation windings, therefore, at the generator output, the voltage value changes with a change in the rotational speed of the rotor 5, since the magnetic flux Ф is created magnets and practically does not change. Therefore, at the input of the voltage regulator unit 21, the variable voltages coming from the generator output are stabilized within predetermined limits using, for example, parallel resonant circuits containing a capacitance and a saturation choke, or devices with semiconductor converters, etc. (see website: https://studbooks.net/83035/tehnika/sinhronnye_generatory_postoyannymi_magnitami).

In the proposed device, the initial speed of the carriage, which ensures the operation of the voltage regulator unit 21 (first of all, the beginning of the battery charge in this voltage regulator unit 21), is significantly lower (≈ 10 km / h) than that of the generators used today with an excitation winding, at which the initial speed of the carriage Vbegin = 30-35 km / h. This advantage is obtained due to the fact that in the working gap 6 between the poles of the rotor 5 and the stator 4 in the present invention there is always a magnetic flux F, which is ensured by using high-energy permanent magnets 1 on the rotor 5. magnets produced today based on rare earth materials of the NdFeB type (see TU 6391-004-59990452-2009. Sintered NdFeB (neodymium-iron-boron) magnets), which have a high coercive force and residual induction in magnetization, and are weakly sensitive to the value of non-magnetic gap in the magnetic circuit.

The rotor 5 with holes for its cooling 17 is made in the form of assembled discs 22 made of non-magnetic material of a certain thickness, for example, 1 mm. An even number of tangentially magnetized permanent magnets 5 are installed along the perimeter of the rotor discs 22 in rectangular windows 23, forming P pairs of adjacent permanent magnets 1, counter-magnetized in each pair. Between each pair of permanent magnets 1 in the windows 24, poles 7 made of ferromagnetic iron with holes for their attachment 8 are installed, and therefore P poles 7 are required between the pairs of adjacent permanent magnets 1.

The use of the tangential magnetization rotor in the proposed device makes it possible to obtain working inductions in the air gap 6, which are almost twice the induction of permanent magnets 1. This is due to the fact that due to the continuity of the magnetic field lines, the flows through the lateral ends of two adjacent permanent magnets 1 in the air gap 6 are directed in one direction and are folded (see DA Booth. Contactless electric machines. Moscow "Higher school" 1985. Page 63).

It is known (see P.S. Sergeev et al. Design of electrical machines. 1969, pp. 10-12) that the main dimensions of the generator are called the inner diameter D of the stator 4 and its calculated length l _δ , which depend on the power P 'of the generator , its rotational speed n rpm and its electromagnetic loads. The rated power of the generator is determined by:

where

I is the phase current in the stator 4 windings, an increase in which is accompanied by an increase in the wire diameter in the stator 4 windings (an increase in the size of the stator 4);

E is the electromotive force of the stator 4, which is directly proportional to the number of turns ω in the stator windings 4, an increase in which leads to an increase in the size of the stator, and to the magnetic flux Ф, determined from the actual field curve.

The formation of the optimal magnetic flux Ф is ensured by choosing the number of poles 7 of the rotor 5, formed by permanent magnets 1 of the corresponding type, as well as maintaining the required air gap 6 between the stator 4 and the rotor 5.

The utilization factor K _{A of the} generator:

the specific power of the generator is determined.

The theoretically substantiated characteristics of the generator in the proposed invention, significantly superior to the characteristics of the generator (analogue) used today in railway transport (comparison of characteristics with the prototype is impractical, since the prototype presents its use with powers an order of magnitude lower than required), were confirmed by the practical implementation of the generator in the form of a prototype a sample made in JSC "NIIEM" (is the Applicant of the invention), which are shown in table 1:

Thus, the use of the proposed generator device with excitation from permanent magnets makes it possible to obtain:

• high specific power of the generator;

• high efficiency of the generator;

• high efficiency of the generator by increasing the working inductions in the air gap and ensuring a low initial speed;

• high reliability and active lifetime of the generator over 30 years.

Claims (1)

A permanent magnet excited synchronous generator device including a generator body; a rotor with permanent magnets of an even number fixed on it, mounted on bearings in the generator housing and mechanically connected to the drive from the axle of the wheelset of the moving car; a stator, the windings of which are connected by lead wires to a terminal box connected to a voltage regulator unit, while there is an air gap between the rotor and the stator, characterized in that the rotor is a tangential magnetization rotor with holes for cooling and is made in the form of assembled discs made of non-magnetic material, At the same time, permanent magnets with counter-magnetization relative to each adjacent pair are installed in the rotor windows, ferromagnetic iron poles with holes for their fastening are placed between these pairs in other windows, and the stator windings are distributed along the slots on the stator surface with holes for its cooling.

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