EP2533257B1 - Transformer coil - Google Patents

Description

The invention relates to a transformer winding, comprising a strip conductor with a rectangular-like cross-section and external insulation, which is wound in a plurality of both multi-layer radially superimposed and axially adjacent turns arranged around a winding axis, so that a hollow cylindrical winding body is formed.

It is well known that power transformers are used in power supply networks, for example to couple a voltage level of 30 kV to a voltage level of 6 kV. The voltage levels mentioned are relatively small for power grids, which may also have voltage levels of 380kV and higher. Frequently, dry-type transformers are used there, whose nominal power can be, for example, a few 100kVA to 10MVA and higher. Due to the relatively low nominal voltage, in particular on the low voltage side, depending on the rated power of the transformer with correspondingly high currents to be expected, for example, with several hundred amps.

In order to be able to conduct these high currents electrically, the cross section of the winding conductor must be selected to be correspondingly high. In this context, the use of a winding conductor with a rectangular cross-section has proved to be advantageous, because so the filling factor of the available winding window of a Transformer core, on which the transformer winding is disposed opposite to a winding conductor with a round cross-section is used in an improved manner. The fill factor is determined by the ratio of conductor material filled and the available space for the transformer winding. Ideally, the available space is filled as much as possible with conductor material. Thus, the performance of a transformer can be advantageously increased for a given external dimension. Such a winding conductor with a rectangular cross-section, which is also called a strip conductor, may for example have a thickness of 7 mm and a width of 16 mm. The conductor as such is usually made of copper or aluminum and surrounded by an insulating layer, for example, an insulating varnish. This insulating layer is dimensioned such that a voltage stress, as occurs in the operation of the winding, for example, between two adjacent turns, for example, 100V, is held, whereas in adjacent winding layers, the voltage stress is so great that, disadvantageously, an additional insulating layer between adjacent Winding layers is to be introduced.

To avoid or at least reduce such insulation layers, it is also known in the case of winding conductors with a round cross-section to produce windings in the so-called pilgrim step method, as for example in the patent specification DE 829334 described therein, however, for windings of much smaller dimensions than transformer windings for the mentioned performance classes, but rather for LF transformer or ignition coils. This is not - as usual - a complete winding layer along the entire axial extent of the coil wound and then transferred to the next layer. Rather, during the winding process, an overlapping axial reciprocation of a winding conductor guide device with a linear movement along the winding axis achieves an at least partially oblique arrangement of winding regions or winding layers relative to the winding axis. This has the advantage that the effective length of the respective winding layers is shortened and the voltage stress between the winding layers is thus correspondingly reduced. As a result, additional insulation layers between the respective winding layers can advantageously be dispensed with, because typically the insulation of the winding conductor is sufficient for this purpose. However, it proves disadvantageous that due to the winding method to the A layerwise decrease in the winding thickness is unavoidable axial ends of the winding, so that in the end regions unused areas are formed and the fill factor is reduced accordingly disadvantageous.

The WO 2006/126829 A1 discloses a transformer for a light source, which has a winding of a winding conductor with a round cross-section, wherein the winding conductor is wound around a winding axis such that oblique winding disks are formed. As a result, the insulation stress between the conductors of adjacent winding disks is reduced compared to axially extending winding layers. A similar transformer for the backlighting of an LCD display is also used in the US 2002/0140538 A1 disclosed. Also the EP 2003660 A1 discloses a transformer with a comparable winding scheme and a winding conductor with a round cross-section.

Based on this prior art, it is an object of the invention to provide a transformer winding which avoids the above-mentioned disadvantages and in particular has a high fill factor.

This object is achieved by a transformer winding according to claim 1. This is characterized in that by radially superposed turns respective flush radial gaps are formed and the wound strip conductor is guided at least in the majority of turns in a change to an adjacent column in an adjacent winding layer and vice versa, so that parallel oblique winding disks are formed.

The basic idea of the invention is to use a winding conductor with a rectangular cross-section and to arrange or wind it in such a way that both additional insulation layers are avoided and a high filling factor is ensured in the end regions of the winding. To achieve a high filling factor in the end regions of the transformer winding, a matrix-like arrangement of the turns of the winding conductor is provided around the winding axis, namely in flush radial gaps of the respective conductor cross-section, wherein a plurality of radial columns are arranged side by side. As a result, the available winding space is maximally utilized, that is achieved a high fill factor. Such an arrangement is possible only with a winding conductor with a rectangular cross section, but not with a round conductor.

Due to the winding conductor guide according to the invention, namely the preferably simultaneous change of a row and a column after circulation of a respective turn in the respective winding arrangement, obliquely extending parallel winding disks are formed whose length is shorter than the length of a wound over the entire axial length of the transformer winding turntable. Between adjacent winding disks with a simultaneously optimized filling factor of the winding window, a lower voltage stress is given than between adjacent windings Wraps. The voltage stress between adjacent winding conductors of different winding disks or winding layers corresponds to the voltage increase per turn during operation of the winding multiplied by the number of turns to the electrical connection point therebetween. The farther the turns are from the joint, the higher the stress due to the then increased number of turns to the joint. Oblique winding layers are shorter for geometric reasons than the entire axial length of a transformer winding and therefore favor a lower voltage stress. An additional insulation layer can thus typically be dispensed with or at least made thinner, which in turn has a positive effect on the fill factor, since the space obtained can be used for the arrangement of further turns or the winding can also be made correspondingly smaller.

According to a particularly preferred embodiment of the transformer winding according to the invention, the hollow cylindrical winding body is accordingly limited to at least one of its two axial ends by an end surface formed by flush radially superimposed windings so as to increase the fill factor, ie the ratio of space filled and available with conductor material optimize.

According to a further embodiment of the transformer winding according to the invention shortened oblique winding disks are formed at the axial ends of the hollow cylindrical winding body, which are not performed on all winding layers. This is particularly advantageous in the end regions of the hollow cylindrical winding body, so as to fill in the corner regions and thus to further increase the fill factor or to allow an end face formed by a radially superimposed windings arranged one above the other.

According to a further variant of the transformer winding according to the invention, this also has windings in which the wound strip conductor remains in the same winding layer when changing into an adjacent gap, so that an axially extending winding region is formed, whose axial length is shorter than the axial length of the winding Winding body, wherein arranged according to a further variant of the invention, at least two axially extending winding areas radially one above the other are. By shortening the length of the axial winding regions, the voltage stress between the respective winding regions is advantageously reduced, so that even in this case typically an additional insulation layer can be dispensed with. However, the majority of the turns is arranged according to the invention in parallel oblique winding disks. The background to this is that the thickness of a transformer winding or of a winding cross section formed by the wound winding conductor is normally significantly smaller than the axial length of a transformer winding. Therefore, in the oblique arrangement with a radial component, it is relatively easy to achieve a small number of turns per winding disk, which usually corresponds at least in the axially middle region of the transformer winding to the number of winding layers. This has an advantageous effect on a reduced stress load.

A further variant of the invention is that a respective insulation layer is provided between adjacent winding disks and / or radially superposed axial winding areas. This is an optional additional solution in the event that the insulation of the winding conductor is not sufficient for the insulation between adjacent winding layers or winding disks, for example due to a very high nominal voltage. In the event that such an insulating layer should be necessary, however, this is correspondingly thinner perform. As insulation material, for example, a wound resin-impregnated (glass) fiber roving is suitable, which is then baked in the further manufacturing process of the transformer winding.

According to a further variant of the invention, the hollow cylindrical winding body comprises a further, galvanically separated hollow cylindrical winding, which connects radially outside or radially inside. This is, for example, a high-voltage winding, which cooperates with the underlying and then used as a low-voltage winding transformer winding during operation of the transformer. Preferably, a hollow cylindrical cooling passage is provided between the two windings, which in operation of the transformer winding, the resulting Dissipates heat loss. This can of course also be in the form of a plurality of annularly arranged segment-like individual channels. Particularly in the case of dry-type transformers, for which the winding according to the invention is typically provided, in contrast to oil transformers, the task of dissipating the heat loss arising during operation is increasing. In oil transformers, the insulating medium oil also acts as a cooling medium.

The advantages of a transformer winding according to the invention also become apparent for a transformer comprising at least one transformer core and a transformer winding according to the invention. Preferably, however, a transformer is designed in three phases in order to be able to be used in typical power distribution networks.

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 Schnitt durch eine exemplarische erste Transformatorwicklung,

Fig. 2

einen Teilschnitt durch eine exemplarische zweite Transformatorwicklung,

Fig. 3

einen Bandleiter mit rechteckähnlichem Querschnitt sowie

Fig. 4

Seitenansicht auf Teil von einer dritten Transformatorwicklung.

Show it:

Fig. 1

a section through an exemplary first transformer winding,

Fig. 2

a partial section through an exemplary second transformer winding,

Fig. 3

a strip conductor with a rectangle-like cross-section as well

Fig. 4

Side view on part of a third transformer winding.

Fig. 1 shows a section through an exemplary first transformer winding 10. Arranged around a winding axis 38 is a hollow cylindrical transformer winding, which is formed from a plurality of turns of a winding conductor, wherein the beginning of the winding conductor by the reference numeral 12 and the end of the winding conductor by the reference numeral 14 is. In the sectional view, the winding conductor is arranged in a matrix-like manner radially around the winding axis 38, that is to say in respective flush radial gaps 22, 24, 26 and respective adjacent winding layers 16, 18, 20. The winding sense of the winding conductor - ie not the conductor course itself - is characterized by a dashed line which extends meandering between the beginning 12 and end 14 of the winding conductor. The first turn begins in the sectional view at the bottom left with the reference numeral 12 and goes at its end, ie after 360 °, into the second turn, which begins in the same winding layer 16 in the second radial gap 24. In the further winding course, parallel oblique winding disks are formed by the respective column and position offset, of which an exemplary winding disk is designated by the reference number 30. At the end of a respective winding disk, a change takes place to the respective adjacent winding disk, as indicated by the reference numerals 32, 34 and 36. In the figure, a distance between adjacent turns is indicated in the radial and axial directions, which in reality is only marginally present, if at all. The winding conductor is coated according to the invention with a layer of insulating varnish, so that adjacent turns are insulated from each other.

In the lower part of the figure, the almost identical cross-sectional contour necessarily present on the other side of the rotation axis 38 is shown simplified with a rectangle with the reference number 46. The hollow cylindrical winding body formed by the winding conductor is fitted into a hollow cylindrical bobbin 40 adapted in shape. The existing space within the bobbin 38 space is exploited by the selected winding conductor arrangement to a large extent, so that a correspondingly high fill factor is given. The perpendicular to the winding axis extending end faces are indicated at the cross-sectional contour by the reference numerals 42 and 44.

Fig. 2 shows a partial section through an exemplary second transformer winding 50. This corresponds essentially to the transformer winding from the previous figure, but has a changed sense of winding on. In the left-hand region, axially extending winding regions are formed within the first three left-hand radial radial gaps, as indicated by the reference numerals 58 and 60. These go on their side facing away from the first end face 64 of the transformer winding on in oblique winding disks, which are indicated by the reference numerals 52, 54, 56. The winding disk with the reference numeral 56 is shortened, so as well as in fill the figure shown on the right top of the transformer winding and thus increase the fill factor. The second end face of the transformer winding is indicated by the reference numeral 62.

Fig. 3 shows a ribbon conductor 70 with a rectangular-like cross-section, which has an inner conductor 72 made of copper or aluminum and which is surrounded by an insulating layer 74. The height of such a strip conductor is for example 2mm to 10mm and the width, for example, 7mm to 30mm. The thickness of the insulation layer is - depending on requirements - for example, 50 .mu.m to 200 .mu.m.

Fig. 4 shows a side view of a part of a schematically very simplified illustrated third transformer winding 80. To a winding axis 82 are arranged at a radial distance and adjacent to each other, a first 84, a second 86 and a third winding 88 of a winding conductor. A position change between the various turns is schematically indicated by the reference numerals 90 and 92.

LIST OF REFERENCE NUMBERS

10

Section through exemplary first transformer winding

12

Beginning of the band leader

14

End of the band leader

16

first winding layer

18

second winding layer

20

third winding layer

22

first radial column

24

second radial column

26

third radial column

30

sloping winding disc

32

radially inward column change

34

radially outward column change

38

winding axis

40

bobbins

42

first end face of first transformer winding

44

second end face of the first transformer winding

46

Cross-sectional contour of the first transformer winding

50

Partial section through exemplary second transformer winding

52

first sloping winding disk

54

second oblique winding disk

56

third oblique shortened winding disk

58

first axially extending winding area

60

second axially extending winding area

62

second end face of the second transformer winding

64

first end face of second transformer winding

70

Band conductor with a rectangle-like cross-section

72

metallic conductor

74

insulation layer

80

Side view on part of third transformer winding

82

winding axis

84

first turn

86

second turn

88

third turn

90

first layer change of the conductor

92

second layer change of the conductor

Claims (9)

1. Transformer winding (10, 50, 80) for a power transformer, comprising a ribbon conductor (12, 14, 70) having a near-rectangular cross section and outer insulation (74) consisting of a coating of insulation enamel, which ribbon conductor is wound around a winding axis (38, 82) in a multiplicity of turns (84, 86, 88), which are arranged both in a plurality of layers (16, 18, 20) radially one on top of the other and axially adjacent, so that a hollow-cylindrical coil former is formed, wherein respective flush radial columns (22, 24, 26) are formed by turns (84, 86, 88) arranged radially one on top of the other, and the wound ribbon conductor (12, 14, 70) is also guided in an adjacent winding layer (16, 18, 20), at least in the case of the plurality of turns (84, 86, 88) on a change to an adjacent column (22, 24, 26), and vice versa, with the result that parallel winding discs (30, 52, 54, 56) running at an angle to one another are formed.
2. Transformer winding according to Claim 1, wherein the hollow-cylindrical coil former is delimited at at least one of its two axial (38, 82) ends by an end face (42, 44, 62, 64) which is formed by turns (84, 86, 88) which are arranged flush radially one on top of the other.
3. Transformer winding according to either of Claims 1 and 2, wherein shortened winding discs (56) running at an angle are formed at the axial (38, 82) ends of the hollow-cylindrical coil former, said winding discs not being guided over all winding layers (16, 18, 20).
4. Transformer winding according to one of the preceding claims, wherein said transformer winding also has turns (84, 86, 88) in which the wound ribbon conductor (12, 14, 70) remains in the same winding layer (16, 18, 20) on a change to an adjacent column, with the result that an axially (38, 82) running winding region (58, 60) is formed, whose axial (38, 82) length is, however, shorter than the axial length of the coil former.
5. Transformer winding according to Claim 4, wherein at least two axially (38, 82) running winding regions (58, 60) are arranged radially one on top of the other.
6. Transformer winding according to one of the preceding claims, wherein a respective insulation coating is provided between adjacent winding discs (30, 52, 54, 56) and/or axial winding regions (58, 60) arranged radially one on top of the other.
7. Transformer winding according to one of the preceding claims, wherein the hollow-cylindrical coil former comprises a further, galvanically isolated hollow-cylindrical winding, which adjoins radially.
8. Transformer winding according to Claim 7, wherein a preferably hollow-cylindrical cooling channel is provided between the two windings.
9. Transformer comprising at least one transformer winding according to one of Claims 1 to 8.

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