RU197778U1 - LONGITUDINAL EXCITATION GENERATOR - Google Patents

Abstract

The utility model relates to electrical engineering and is an electric machine designed to generate voltage. Various constructions of electrical machines are known from the prior art, including using permanent magnets to excite EMF in their output windings to supply DC loads. The use of permanent magnets as a substitute for the pole windings provides an improvement in the mass and dimensions of the electric machine as a whole. For technological reasons, the use of a set of magnets to form the magnetic poles of the rotor is impractical (lower reliability, complex assembly). Therefore, to excite the magnetic flux, one magnet is used, mounted in the center of the rotor and magnetized in the longitudinal axis of rotation, sets of poles are installed on the sides of such a magnet. In all such constructions known from the theory, claw-shaped poles of the rotor are used to ensure alternating polarity of the magnetic flux. This increases the mass of the rotor, complicates the design and its manufacture, and leads to the need to manufacture the stator entirely from magnetic material (increase in stator mass). The proposed solution describes a permanent magnet generator that has the advantages of excitation from a permanent magnet, but without the disadvantages of known generators with claw-shaped rotor. The basis of his work is the creation of a magnetic system with a longitudinal path of magnetic flux, while the magnetic force lines are closed through separate magnetic circuits located (fixed) in a non-magnetic stator. The difference of the proposed solution is the location of the stator coils in the middle of the magnetic cores, having a rectangular cross section along their entire length; slots for coils are made in a non-magnetic stator. In the region of each set of rotor poles, rings made of magnetic material are installed on the stator, which ensure smoothing of the magnetic field for magnetic cores that do not have a tooth zone.

Description

The technical field to which the utility model belongs. The utility model relates to electrical engineering and is an electric machine designed to generate voltage.

State of the art

The prior art unipolar current generator [RF patent for the invention No. 2518461], containing a rotating rotor and a fixed stator. As a rotor rotating in a perpendicular magnetic field, a stacked disk of metal plates (disk sectors) is used, separated by dielectric spacers, with sliding contacts on the axis of rotation of the disk. As a fixed stator, the poles of a rotating constant or alternating magnetic field are used, and the number of sectors of the rotor is equal to the number of stator poles or more, and the stator poles of a rotating magnetic field can be created by rotating magnets, or electromagnets, or fixed windings with a magnetic circuit inside, in which a rotating constant or variable field. The number of rotating poles can be 2 or more, subject to the condition that the directions of the EMF created by the diametrically arranged poles in the rotor are aligned, and the adjacent poles (along the perimeter) create alternating directions of the diametrical polarity of the EMF on the rotor.

The disadvantages of this solution include the presence of a sliding contact device (current collectors), which reduces reliability.

Also known is a brushless generator [RF patent for utility model No. 195231], comprising a fixed stator with an output winding consisting of coils, a rotor equipped with a cylindrical permanent magnet, sets of poles made of ferromagnetic material installed at its ends and each having a through hole in its center each , with dielectric spacers inside to isolate the plates of the set of poles from the shaft, the rotor, the rotor is made integral with the shaft of non-magnetic material in the center, and the stator is made of non-magnetic material and is equipped with slots for the magnetic cores, each magnetic core is installed in its corresponding slot longitudinally to the direction of the axis of rotation of the rotor and has two teeth protruding into the cavity of the stator cavity, respectively, sets of poles. The number of poles in the kit is one more than half the number of stator magnetic circuits, with the number of stator magnetic circuits a multiple of two.

This decision is made by the main prototype, the closest in its technical essence.

The disadvantages of this solution include the presence of a toothed zone of the stator magnetic circuits, which complicates their design, and also makes it impossible to smooth the magnetic flux by manufacturing teeth with extensions.

Utility Model Disclosure

The prior art various designs of electrical machines [1, 2]. Many of them use permanent magnets to obtain a magnetic flux of excitation, which leads to the appearance of a variable EMF in the generator windings during their mechanical rotation. Solutions are possible that use field windings to produce magnetic flux - most of them require mechanical contact, for example, rings on the rotor with brushes for their operation. Thus, the use of permanent magnets to obtain magnetic flux simplifies the design and eliminates the contacts for transmitting current to the field winding. In addition, permanent magnets can improve the efficiency of an electric machine, and often significantly reduce the weight and dimensions - since modern materials for magnets have a high coercive force and are able to replace field windings with high field currents in small dimensions, and the field windings determine the machine for dimensions generally.

The successes of modern industry in the extraction and processing of rare-earth metals, as well as the manufacture of permanent magnets with a high value of coercive force (and magnetic induction) have ensured the serial production of various electric machines with magnetic poles from permanent magnets. Significant capacities are available, up to 1-3 MW. Permanent magnets of various shapes are available.

And although the engines make up a significant part of the manufactured machines with permanent magnets, the generation of electricity is also relevant. Replacing the excitation winding of the rotor of the synchronous generator with permanent magnets allows you to get rid of the contact rings on the rotor and the brush apparatus for transmitting current to the rotor windings, but provides only alternating current at the output. One way to improve the reliability of alternating current and alternating current generators is to eliminate or minimize the number of current collectors and mechanical brush contacts [1]. The presence in the design of the classic brush generator generators leads to wear of the brushes and the need for their maintenance, as well as to the release of coal dust into the surrounding air.

The proposed solution is the completion of the design of the DC generator, with the closure of the magnetic field lines in the direction longitudinal to the axis of rotation of the rotor and is aimed at improving the design and assembly technology of such a generator.

The solution proposed by the author is based on the use of an excitation field of the same polarity to form the output voltage. As you know, any source of a magnetic field has poles: north (N) and south (S), the lines of force of which are closed among themselves, forming a closed loop for the passage of magnetic flux. Alternating the polarity of the poles is not required to generate the output voltage, however, the only way to avoid changing the polarity is to excite the magnetic field longitudinal to the axis of rotation of the rotor.

In the designs of direct current generators known from the literature, the magnetic field is excited by the installation of permanent magnets on the rotor of the generator, and always the magnetic poles alternate with their polarity “north” and “south”. Various designs of a permanent magnet rotor are known, including in the form of claw-shaped poles [2], however, in all of them the poles are arranged with alternating polarity. With this construction of the magnetic system of electrical machines, the magnetic flux closes in a plane transverse to the axis of rotation of the rotor, which leads to the need to manufacture the stator entirely from magnetic material. In turn, such a stator will be inevitably massive, and its production will be technologically difficult due to the round shape of the sheets from which the magnetic circuit package of such a stator is assembled.

However, an alternative machine design is possible, shown in FIG. 1, which shows the appearance of a longitudinal excitation generator assembly. It is obvious from the figure that the generator rotor does not have claw-like bends of the pole packets installed at its ends. In this case, the direction of the magnetic flux of the excitation never changes its sign. The poles in the package provide the distribution of the excitation flux along the stator magnetic circuits, on which the output winding coils are installed. The magnetic flux passing through the stator coils does not change its sign, its absolute value ranges from zero to a maximum of one sign of polarity.

The figure 2 shows the magnetic system of the proposed generator with longitudinal excitation. The figure shows the gear structure of the poles in the sets installed in the longitudinal to the rotation axis of the magnetic circuit with the output winding coils installed in their middle. You can also see the stator rings installed inside its cavity in the region of the poles of the rotor. Such rings are installed to smooth the magnetic flux from the poles of the rotor and the formation of a better voltage. Such rings are replaced by extensions of the stator teeth, as is realized in classical electric machines with a half-closed groove. The installation of the output winding coils in the middle of the magnetic cores installed in the slots of the non-magnetic stator housing facilitates the assembly process. With a rectangular cross section of the stator magnetic circuits, on which the individual coils are located, that is, in the absence of protrusions (teeth), it is possible to manufacture coils on the machine, and then easily install them (putting them on) on the magnetic circuit. After that, the magnetic circuit with the coil is inserted into the slot from the inside of the non-magnetic stator housing, and the coil, with one of its sides, goes into the through hole in the stator housing. This facilitates the thermal mode of its operation (heat removal to the outside of the housing). This design is the simplest and easiest in terms of manufacturing technology of parts and assembly. This provides economic benefits to such a generator.

Figure 3 shows a longitudinal section of the proposed generator, where its component parts are visible - a non-magnetic stator housing, magnetic cores made of ferromagnetic material, on which the output winding coils are mounted. A set of rotor poles is also visible, from which the difference from the claw-shaped rotor is obvious - there is no bending of the poles in the sets on the rotor. The figure shows the direction of the magnetic lines of force flowing in the direction longitudinal to the direction of the axis of rotation of the rotor and excited from the magnet in the center of the rotor. The direction of the magnetic flux never changes sign.

The figure 4 shows a cross section of a generator with longitudinal excitation in the area of installation of the stator coils. That is, a section is made in the middle of the generator stator across the axis of its rotation. The figure shows the coils mounted on a rectangular cross section of the magnetic cores, also shows the cross section of the permanent magnet in the center of the rotor.

The figure 5 shows a cross section of the proposed generator with longitudinal excitation in the region of the set of poles of the rotor. The figure shows a non-magnetic stator housing, equipped with slots in the internal cavity, in which magnetic circuits with coils are installed on them. You can also see the package of rotor poles and the inside of the ring made of magnetic material to smooth the distribution of magnetic flux, since the rectangular shape of the stator magnetic circuits does not allow to obtain a fairly uniform distribution of magnetic flux around the circumference. This can lead to significant non-linearities and voltage beats; for this, in the proposed solution, inserts (rings) are used from the inside of the stator cavity in the region of the pole sets. Their thickness is determined in each case individually when designing the generator, taking into account the balance between the quality of voltage and the level of output voltage.

The presented solution is simple and therefore industrially applicable, providing ease of manufacture of components and the process of assembly of the generator with longitudinal excitation. An exception was achieved from the design of the complex shape of the stator magnetic cores with protrusions, instead of which the arrangement (putting on) of coils in the middle of each of the magnetic cores, and the installation of rings of ferromagnetic material from the inside of the stator cavity, which smooths the distribution of the magnetic flux of the poles around the circle and the formation of a better output shape voltage.

The proposed technical solution is new, and has the following fundamental differences from the main prototype:

- a fixed stator of non-magnetic material has slots for magnetic cores of ferromagnetic material longitudinally to the axis of rotation, and the slots are made through at the installation site of the output winding coils;

- the stator is equipped with rings of ferromagnetic material installed internally in the vicinity of pole sets of ferromagnetic material;

- winding coils are placed in the middle of magnetic cores of ferromagnetic material;

- magnetic cores have a rectangular cross section along the entire length.

Thus, the entire set of essential features of the utility model is previously unknown and leads to a new technical result - simplification of the generator design and its assembly technology.

A brief description of the drawings. The figure 1 shows the appearance of the generator with longitudinal excitation assembly. The figure 2 shows the appearance of the magnetic system of the generator with longitudinal excitation with installed coils. The figure 3 shows a longitudinal section of a generator with longitudinal excitation. Here 1 is a non-magnetic stator housing, 2 is a ferromagnetic magnetic circuit, 3 is a ferromagnetic ring, 4 is a set of rotor poles, 5 is a coil. The figure 4 shows a cross section of a generator with longitudinal excitation in the area of installation of the coils. The figure 5 shows a cross section of a generator with longitudinal excitation in the region of the set of poles of the rotor. Here 1 is a non-magnetic stator housing, 2 is a ferromagnetic magnetic circuit, 3 is a ferromagnetic ring, 4 is a set of rotor poles.

List of used literature.

1. Kopylov I.P. Design of electrical machines. M .: Publishing house "Yurait", 2014.

2. Stelting G., Beiss A. Electric machines. M .: Publishing house "Energoatomizdat", 2015.

Claims (1)

An electric generator with a permanent magnet excitation, comprising a fixed stator made of non-magnetic material, an output winding consisting of coils, a rotor equipped with a cylindrical magnet, sets of poles made of ferromagnetic material from the ends of the rotor, output winding coils mounted on magnetic circuits made of ferromagnetic material, characterized in that a fixed stator made of non-magnetic material has slots for magnetic cores made of ferromagnetic material longitudinally to the axis of rotation, the said slots are made through at the installation site of the output winding coils, the stator is equipped with rings of ferromagnetic material installed internally in the vicinity of the pole sets of ferromagnetic material, the output winding coils are placed along in the middle of the magnetic cores of ferromagnetic material, the magnetic cores of ferromagnetic material themselves have a rectangular cross section along the entire length.

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