EP2800109A1 - Polygonal transformer core and transformer with polygonal transformer core - Google Patents

Abstract

The invention relates to a polygonal transformer core (70, 90) comprising a band-like metallic strip (10, 30, 40, 50) wound in a spiral or ring-like polygonal manner around a winding axis (72) with cyclic (20) recesses (12, 32, 48 ), wherein through the cyclic (20) recesses (12, 32, 48) along the extension of the band-like strip (10, 30, 40, 50) extending longitudinal regions (14, 16, 34, 42, 52) and transversely extending transverse regions (18, 36, 44, 54) are formed, wherein the metallic strip (10, 30, 40, 50) is wound in such a way and the cyclic (20) recesses (12, 32, 48) are arranged such that wound state of the metallic strip (10, 30, 40, 50) over all winding layers (80, 82, 84, 98, 100, 102, 104) across a respective at least approximately congruent common recess region is formed, which has a respective winding window (92 ) of the transformer core, wherein by stacking lying longitudinal regions (14, 16, 34, 42, 52) respective transformer core yokes (96) are formed and wherein by superimposed transverse regions (18, 36, 44, 54) respective transformer core legs (94) are formed. The invention also relates to a transformer with a transformer core according to the invention.

Description

The invention relates to a polygonal transformer core and a transformer with a polygonal transformer core.

It is well known that transformers are used in power distribution networks to accommodate different voltage levels, such as 10kV, 30kV, 60kV or 110kV. Power distribution grids are typically three-phase, which also uses three-phase transformers. Such three-phase transformers usually have three transformer core legs, which pass through a respective coil with primary and secondary windings. The galvanically isolated coils are coupled via a magnetic flux, which is guided by the transformer core with its core legs and core yokes.

The core legs of the transformer core usually run parallel to each other in the same plane, the respective floor plans of the transformer core legs are thus arranged along a straight line. Thus, a transformer core typically has a parallelepiped-like shape with two also cuboidal recesses for a respective winding window. The recesses for the winding windows then form respective transformer core legs and transformer core yokes.

However, a disadvantage of such a transformer core shape proves that this is characterized by a certain asymmetry, which also affects the electrical performance. From a thermal point of view, the middle coil in each case is exposed to increased heat radiation through the two adjacent coils. In addition, a transformer with such a core shape requires an increased space requirement.

To counteract such disadvantages, according to the prior art, transformer cores of polygonal outline are known, in particular with a triangular plan. In such a core, the floor plans of the legs are not arranged along a line but at the vertices of an in-plane polygon, preferably an equilateral triangle.

Such a polygonal or triangular transformer core is made according to the prior art from three wound window-like core modules, which are arranged at an angle to each other adjacent to respective transformer core leg halves. The disadvantage here is that such a transformer core is complicated to manufacture due to the different modules. In addition, the width of the wound strip, from which the window-like modules are made to vary depending on the winding layer, which also proves to be costly.

Based on this prior art, it is an object of the invention to provide a polygonal transformer core, which is particularly easy to manufacture. This object is achieved by a polygonal transformer core according to the invention. This comprises a spiral or ring-like polygonal wound around a winding axis band-like metallic strips with cyclic recesses, which are formed by the cyclic recesses along the extension of the band-like strip extending longitudinal regions and transversely extending transverse regions, wherein the metallic strip is wound and the cyclic Recesses are arranged such that, in groups, a respective at least approximately congruent common cut-out area is formed by these in the wound state of the metallic strip over all winding layers, which represents a respective winding window of the transformer core, wherein superimposed longitudinal regions respective transformer core yokes are formed, and wherein respective transformer core legs are formed by superimposed transverse regions.

The basic idea of the invention is to arrange a continuous metallic strip with recesses in a spiral-like shape in such a way that a polygonal transformer core is thereby formed. The recesses are arranged approximately congruent in groups over all winding layers, so that respective winding windows are thereby formed. By using only a single band-like strip, the production of a polygonal transformer core is advantageously simplified.

According to a particularly preferred embodiment variant of the polygonal transformer core according to the invention, the respective cyclic spacing of the recesses in the longitudinal direction takes into account a different winding radius of different winding layers and the sum of the cyclic distances of each winding layer corresponds exactly to an angle of 360 °. The larger the winding radius, the greater the length of a circumferential winding layer. In the event that a layer change of the strip takes place, for example every 90 ° and thus more than once per revolution, this of course also applies to the relevant section of the situation. If the cyclic recesses or their distances are extended correspondingly in the case of radially outer layers, it is advantageously achieved that the cyclic recesses are approximately congruent over all winding layers.

According to a further preferred embodiment variant of the polygonal transformer core, the recesses were removed from an originally continuous metallic strip. This allows a particularly simplified production of a transformer core. The metallic strip is then unrolled, for example during the manufacturing process in a continuous process from a supply roll and the recesses are removed, for example by punching or laser cutting. Subsequently, the thus provided with cyclic recesses tape is rolled up again and the polygonal transformer core is formed. Of course, in addition to a simple rolling process, which too leads a respective ring-like yoke, also a buckling at the vertices of the polygonal outline of the transformer core to be formed possible, so that the respective yoke also assumes a polygonal shape.

According to a further embodiment of the polygonal transformer core according to the invention, the recesses of the metallic strip are window-like pronounced, so it is on both sides of the recesses each provided a transverse region. This has the advantage that the transformer yokes formed by the transverse regions on the one hand are designed solid and on the other hand, in their shape and their cross-section can be varied almost arbitrarily. It is thus possible, for example, to determine the cross-sectional shape of the yokes, but also those of the legs, by corresponding variation of the width of the recesses between the individual layers. Normally preferred is a circle-like cross-section.

In order to obtain the greatest possible freedom in the design of the cross sections of the yokes, it is useful to provide a mutual correction possibility for the width of the currently processed metallic strip in the production process of the transformer core, for example a laser cutting device or the like.

According to a further variant of the polygonal transformer core of the metallic strip is meander-shaped and the recesses are alternately provided on each side of the metallic strip. Such recesses are easier to manufacture. Magnetically, the omission of every second winding layer in the yoke regions can be compensated by a correspondingly broadened yoke cross section.

According to a further preferred embodiment variant, the meander-shaped metallic strip having alternating recesses has been produced by cyclically folding, bending or bending a continuous narrower metallic strip. This has the advantage that a material throw caused by removal of recess areas from a wider metallic strip is advantageously avoided.

This variant of the invention is characterized by a simple manufacturing process. For example, the narrower metallic strip, which may have an exemplary width of 30 cm, is first provided on a roll and continuously unwound during manufacture of the transformer core. In a subsequent continuous folding, bending or bending process, the course of the band is changed, for example, alternately by +/- 90 °. Thus, a wider meandering strip is formed with a width of, for example, 1.8m. In the case of a respective folding of the strip, the strip thus formed, with the exception of the folding points, corresponds approximately to a meandering strip in which the cutouts have previously been removed. This can thus also be transformed into a roll-like process in a simple manner to a polygonal transformer core.

In the case of a meandering metallic strip, the number of transformer core legs formed is three or more odd numbers. In the case of an even number, the alternating yoke regions would always lie one above the other, and thus no yoke would be formed in each case, which has a negative effect on the magnetic properties of the transformer core.

According to a further embodiment of the polygonal transformer core according to the invention, the metallic strip runs with its cross section in a spiral-like polygonal running around the winding axis plane. For this purpose, the metallic strip is preferably to be folded to the desired meandering shape. In such a case, the strip or the metallic strip formed by its meandering fold can be rolled in a simple manner into a transformer core according to the invention.

According to an alternative embodiment of the polygonal transformer core, the metallic strip runs with its cross section both in the longitudinal regions and in the transverse regions in a respective plane radially or transversely to the winding axis. Compared to the alternative embodiment mentioned above, the band is therefore basically rotated by 90 ° in the orientation of its cross section. For this purpose, the metallic band is preferably to bend or buckle. Depending on the number of Corners of the polygonal plan or the number of transformer core legs is still an angle to consider when kinking, in which the kink in relation to the elongated extent of the band runs. For an equilateral triangular floor plan this would be 60 ° each, for an equilateral pentagonal floor plan 108 °. If necessary, the kink can also include a fold.

In contrast to the aforementioned embodiment, in which the winding layers are arranged radially next to one another, in this case the adjoining longitudinal or transverse regions of the meandering band extend axially or tangentially adjacent to the winding axis. In order to avoid crossing the different band areas, it is advisable, for example, to arrange the band in two interleaved hollow cylindrical areas around the winding axis, wherein the band alternately for a first angular range about the winding axis in each radially inner and then for a second angular range in the radial outer hollow cylindrical area extends. If necessary, additional folds should be provided for changing within the cylindrical areas.

In the event that the band-like metallic strip is ultimately formed of a meander-shaped bent metal wire, folds can be avoided due to the then partially round and not flat cross-section and the arrangement of the wire along its extension can also have torsions or the like, thus simplifying the production is.

According to a further variant of the polygonal transformer core according to the invention, a transformer core leg is formed at each corner point of the polygonal winding plan. As a result, the production of the transformer core is advantageously simplified.

According to a particularly preferred embodiment of the polygonal transformer core according to the invention, the metallic strip or the narrower metallic strip, from which the metallic strip with its recesses can likewise be formed according to the invention, is manufactured from an amorphous strip material. Amorphous core materials are characterized by improved magnetic properties, which allow a further increased efficiency of a corresponding transformer. On the other hand, such a material is only available as extremely thin and mechanically very sensitive band material. Due to a limited available width of the strip material, the realizable sizes of a transformer core are limited, for example, to a rated power of 2MVA. In addition, the magnetic advantages of an amorphous core material can be achieved only within a corresponding temperature range, so it is an increased cost for the cooling of such a transformer core of amorphous strip material necessary.

The use of a single amorphous strip for producing a complete transformer core makes it mechanically more stable and thus compensates within certain limits the mechanically unfavorable properties of an amorphous strip material. In addition, manufacturing using a strip material provided on rolls can be advantageously automated to a very high degree.

Further advantageous embodiment possibilities can be found in the further dependent claims.

Reference to the embodiments illustrated in the drawings, the invention, further embodiments and other advantages will be described in detail.

Fig. 1

einen ersten exemplarischen bandähnlichen metallischen Streifen,

Fig. 2

einen zweiten exemplarischen bandähnlichen metallischen Streifen,

Fig. 3

einen dritten exemplarischen bandähnlichen metallischen Streifen,

Fig. 4

einen vierten exemplarischen bandähnlichen metallischen Streifen,

Fig. 5

einen exemplarischen Herstellungsablauf für einen ersten Transformatorkern,

Fig. 6

einen schematischen exemplarischen zweiten Transformatorkern sowie

Fig. 7

einen schematischen exemplarischen dritten Transformatorkern.

Show it:

Fig. 1

a first exemplary band-like metallic strip,

Fig. 2

a second exemplary band-like metallic strip,

Fig. 3

a third exemplary band-like metallic strip,

Fig. 4

a fourth exemplary band-like metallic strip,

Fig. 5

an exemplary production process for a first transformer core,

Fig. 6

a schematic exemplary second transformer core as well

Fig. 7

a schematic exemplary third transformer core.

FIG. 1 shows a first exemplary band-like metallic strip 10 in a schematic plan view. The strip 10 is made of an amorphous strip material having, for example, a thickness of 100 μm and a width of 30 cm. At cyclic intervals 20 window-like recesses 12 are provided which lie in a grouped congruent superimposed in the rolled-up state of the strip 10 and form a respective winding window. Respective transverse regions 18 and respective longitudinal regions 14, 16 are formed on both sides of the recesses 12, which in the rolled-up state of the metallic strip 10 are also congruently superimposed in groups and form respective limbs or yokes. The respective recesses have been removed by means of a laser cutting method.

FIG. 2 shows a second exemplary band-like metallic strip 30 with alternating lateral recesses 32. By the recesses 32 longitudinal regions 34 and transverse portions 36 are formed at their edges, which are in a rolled together state of the strip 30 each group in a congruent superimposed and form respective yokes or legs. The strip is made of a painted transformer sheet having an exemplary thickness of 0.5mm and a width of 1.5m. Although the roles represents the simplest way to transform the strip 30 into a transformer core, if necessary, also offers a buckling at the corners of the polygonal plan to be formed, as indicated by the dashed lines. When alternating side cutouts, make sure that the polygonal floor plan has an odd number of vertices. Thus, an upper and a lower yoke region are alternately formed from respective longitudinal regions, thus leaving every second layer in the yoke regions free.

FIG. 3 Figure 3 shows a third exemplary belt-like metallic strip 40 having alternating lateral recesses 48, longitudinal yoke-forming sections 42, and leg-forming transverse portions 44. Similar to the metallic strips previously shown, this metallic strip 40 is also provided for a reeling operation. In this example, the metallic strip, which has an exemplary width of, for example, 190 cm, is formed by a folded narrower band of amorphous material, which in turn has a width of 30 cm.

At the respective corner points of the recesses 48, respective folds 46 of the band are provided at an angle of 90 ° in each case, with which the band is meander-shaped around the cutouts or forms them as a result. Amorphous material can be subjected to such a fold 46 in the unannealed state without being damaged. In the further production process, the wound amorphous core material is then still glowing in order to achieve the desired magnetic core properties.

FIG. 4 shows a third exemplary band-like metallic strip 50 with alternating lateral recesses, longitudinal regions 52 and transverse regions 54. In this example, the metallic strip 50, which for example has a width of 150 cm, is formed by buckling a narrower band of transformer sheet, which in turn has a width of 25cm. Through respective alternating creases 56, the tape is passed around respective recesses. The kinks 56 themselves take place over the material thickness of, for example, 0.3 mm. In order to realize a polygonal floor plan, additional angles across the width of the strip are to be provided between the individual meander loops. These can be realized either by a twist of the band in the transverse regions 54 or by an additional folding in the longitudinal regions 52. If necessary, however, the kinks 56 can also be angled. In the case of an equilateral triangle as floor plan, the respective torsion, folding or bending angle is 60 ° in each case. In order to avoid overlaps in the arrangement of the metallic strip 50 about a winding axis, it is advisable to arrange the strip in two nested hollow cylindrical areas. Thus, first a turn with 360 ° may be formed in the inner cylinder, then takes place by means of an additional folding a change to the outer cylinder. With an odd number of legs to be formed then the respective yoke regions formed in the inner and in the outer cylinder are offset from each other. An upper yoke in the inner cylinder is then opposed by a lower yoke in the outer cylinder.

FIG. 5 shows an exemplary manufacturing process for a first transformer core in a picture sequence 60, wherein the letter A indicates the first step and the letter L indicates the last step. With dashed lines is in one Three-dimensional representation of the structure of a triangular transformer core to be formed. With a solid line is indicated that at the respective position already a tape is wound. The solid line marked with an arrow symbolizes the respectively last process step. The metallic strip is formed of a spiral or ring-like arranged around a winding axis arranged meandering band, which is exemplarily performed twice in this example around the winding axis. It is good to see that in the yoke areas only half the number of layers is performed as in the leg areas.

FIG. 6 shows a schematic exemplary second transformer core 70 in a plan view. A metallic strip is arranged around a winding axis 72 following a triangular outline, wherein a respective bend is provided at respective corner points 74, 76, 78. By the spiral-like arrangement a plurality of adjacent winding layers 80, 82, 84 are formed. Cyclic recesses, which form groups of congruent superimposed respective winding windows, are not apparent from this drawing perspective.

FIG. 7 FIG. 1 shows a schematic illustration of a schematic exemplary third transformer core 70 in a three-dimensional representation. A plurality of winding layers 98, 100, 192, 104 of a metallic strip of a transformer sheet with alternating lateral recesses are wound adjacent to one another. The recesses are arranged over the layers 98, 100, 102, 104 away at least approximately congruent and it is thus formed a common recess area, which is a winding window 92. The laterally adjacent to the winding window 92 in groups superimposed transverse regions form each group a respective transformer core leg 94 and the top and bottom groupwise superimposed longitudinal regions each group form a respective transformer core yokes 96. In the yoke regions one winding layer is unoccupied. For technical reasons, only a section of a polygonal transformer core with a single winding window and adjoining leg 94 and yoke areas is shown. Also disregarded in this illustration is a respective angle to adjacent polygon segments. <U> REFERENCE LIST </ u> 10 first exemplary band-like metallic strip 12 window-like recess of the first metallic strip 14 first longitudinal region of the first metallic strip 16 second longitudinal region of first metallic strip 18 Cross area of first metallic strip 20 cyclic distances from the first metallic strip 30 second exemplary band-like metallic strip 32 lateral recess of second metallic strip 34 Longitudinal area of second metallic strip 36 Cross area of second metallic strip 40 third exemplary band-like metallic strip 42 Longitudinal area of third metallic strip 44 Cross area of third metallic strip 46 Folding of third metallic strip 48 lateral recess of third metallic strip 50 Fourth exemplary band-like metallic strip 52 Longitudinal area of fourth metallic strip 54 Cross area of fourth metallic strip 56 Kink of fourth metallic strip 60 Exemplary production process for the first transformer core 70 schematic exemplary second transformer core 72 winding axis 74 first corner 76 second corner 78 third corner point 80 first winding layer 82 second winding layer 84 third winding layer 90 schematic exemplary third transformer core 92 winding window 94 Transformer core leg 96 Transformatorkernjoch 98 first winding layer 100 second winding layer 102 third winding layer 104 fourth winding layer

Claims (12)

A polygonal transformer core (70, 90) comprising a band-like metallic strip (10, 30, 40, 50) with cyclical (20) recesses (12, 32, 48) wound around a winding axis (72) in a spiral or ring-like manner In which longitudinal regions (14, 16, 34, 42, 52) extending through the cyclic (20) recesses (12, 32, 48) along the extension of the band-like strip (10, 30, 40, 50) and transversely extending transverse regions (FIG. 18, 36, 44, 54) are formed, Wherein the metallic strip (10, 30, 40, 50) is wound in such a way and the cyclic (20) recesses (12, 32, 48) are arranged in such a way that they pass through in the wound state of the metallic strip (10, 30, 40 , 50) is formed in groups over each winding layers (80, 82, 84, 98, 100, 102, 104), a respective at least approximately congruent common recess region, which represents a respective winding window (92) of the transformer core, ● wherein by übereinanderliegende longitudinal regions (14, 16, 34, 42, 52) respective transformer core yokes (96) are formed and ● wherein by respective transverse regions (18, 36, 44, 54) respective transformer core legs (94) are formed. Polygonal transformer core according to claim 1, characterized in that the respective cyclic spacing (20) of the recesses (12, 32, 48) in the longitudinal direction takes into account a different winding radius of different winding layers (80, 82, 84, 98, 100, 102, 104) and the sum of the cyclical distances (20) of each winding layer (80, 82, 84, 98, 100, 102, 104) corresponds exactly to an angle of 360 °. Polygonal transformer core according to one of claims 1 or 2, characterized in that the recesses (12, 32, 48) have been removed from an originally continuous metallic strip. Polygonal transformer core according to claim 3, characterized in that the recesses (12, 32, 48) of the metallic strip (10, 30, 40, 50). window-like pronounced, so on both sides of the recesses each have a transverse region (18, 36, 44, 54) is provided. Polygonal transformer core according to claim 3, characterized in that the metallic strip (10, 30, 40, 50) is meander-shaped and the recesses (12, 32, 48) alternately on each side of the metallic strip (10, 30, 40, 50) are provided. Polygonal transformer core according to one of claims 1 or 2, characterized in that the metallic strip (10, 30, 40, 50) meander-shaped and the recesses (12, 32, 48) by cyclic folding (46), bending or buckling (56 ) are formed of a continuous narrower metallic band. Polygonal transformer core according to claim 6, characterized in that the number of formed transformer core legs (94) corresponds to three or a larger odd number. Polygonal transformer core according to claim 7, characterized in that the metallic strip extends in a spiral-like polygonal running around the winding axis plane. A polygonal transformer core according to claim 7, characterized in that the metallic strip in both the longitudinal regions (14, 16, 34, 42, 52) and in the transverse regions (18, 36, 44, 54) in a respective plane radially or transversely to Winding axle (72) extends. Polygonal transformer core according to one of the preceding claims, characterized in that a transformer core leg (94) is formed at each corner point (74, 76, 78) of the polygonal winding plan. Polygonal transformer core according to one of the preceding claims, characterized in that the metallic strip (10, 30, 40, 50) or the narrower metallic strip is made of an amorphous strip material. A transformer comprising a polygonal transformer core according to any one of claims 1 to 11 and at least one winding disposed thereon.

Images