EP2463871B1 - Amorphous transformer core - Google Patents

Description

The invention relates to an amorphous transformer core comprising at least one transformer core disk having a plurality of layers of a ribbon-like amorphous core material arranged concentrically around at least one winding window.

It is well known that transformers for power transmission, for example, at a voltage level of 10kV to 110kV and above, produce core losses during operation. These losses are predominantly due to the re-magnetization losses or hysteresis losses of the commonly used laminated iron core and cause a heating of the same. To reduce these unwanted losses, transformers with cores of amorphous material have also been built recently, which are characterized by reduced core power losses.

However, the use of amorphous materials requires new constructions and processing because, on the one hand, because of the lower flux density compared to a conventional transformer core, larger core cross-sections are required and, on the other hand, an amorphous core material is more sensitive to higher temperatures than a grain-oriented core sheet.

Usually, such transformer cores are made of a thin amorphous strip material, which in a plurality of layers, for example some a thousand, is arranged concentrically around one or even around several winding windows, wherein a sheet usually covers a position, ie a circumferential angle of about 360 °, wherein, if necessary, a slight overlap is realized. Here, a support structure is usually required, by which the core structure is stabilized. In addition, the amorphous material usually available as a flat strip material is mechanically very sensitive. The available widths of the strip material are limited, for example to 200mm. The mechanically realizable sizes of a transformer core are thus limited. Therefore, to realize larger amorphous transformer cores, a plurality of congruent transformer core disks whose width is limited by the width of the available tape material may be juxtaposed and interconnected.

The disadvantage, however, is that with amorphous cores, the cooling of the core is of greater importance than in nuclei of grain-oriented core sheet, since the saturation induction and thus the Nenninduktion of the operating temperature strongly depends. With increasing temperature the possible nominal induction decreases. This must then be compensated by an increased use of materials.

Amorphous transformer cores having a multiplicity of layers of a ribbon-like amorphous material arranged concentrically around at least one winding window are known, for example, from the document EP 2 251 875 known. From the document " Conduction cooled ferrite core in a high power transformer ", IBM technical disclosure Bulletin, Vol. 36, No. 9B, 1 September 1993, ISSN: 0018-8689 and from the document WO 2004/112064 For example, it is known to arrange a plurality of heat conducting plates adjacent at least in sections and to guide them into a common heat exchange area.

Magnetic cores constructed of layered amorphous material having heat conducting sheets interposed therebetween are, for example, the documents JP 60 182116 and WO 94/15346 known. The document JP 60 182116 shows the features of the preamble of claim 1.

Based on this prior art, it is an object of the invention to provide an amorphous transformer core with improved cooling or heat dissipation in order to avoid such an increased use of materials.

This object is achieved by an amorphous transformer core of the type mentioned at the outset. This is characterized in that the at least one heat conduction plate is arranged at least in sections between two adjacent layers of the band-like amorphous core material and led out of at least one side surface of the amorphous transformer core. Wherein at least one Wärmeableitblech extends into the interior of the amorphous transformer core and this is guided from there into at least one heat exchange region outside of the amorphous transformer core, so that an improved dissipation of resulting within the amorphous transformer core heat energy is possible.

The basic idea of the invention is to dissipate heat accumulation arising during operation of an amorphous transformer core in its interior, which leads there to an undesired increase in temperature with a concomitant deterioration of the material properties by outwardly directed to the interior of the core Wärmeableitbleche. The Wärmeableitbleche are made of a material with high thermal conductivity, which is higher in any case than that of the amorphous strip material. Depending on the arrangement and distribution of Wärmeableitbleche inside the core so that better cooling and a more homogeneous temperature distribution inside the core can be achieved. The core cross-section can be carried out advantageously lower. Wärmeableitbleche are due to the structure of an amorphous transformer core of a During production, it is particularly well suited to introduce multi-layered thin amorphous strip material with a limited width into the interior of the transformer core because it is not constructed quasi-monolithically like a standard standard transformer core.

At least one end of such a Wärmeableitbleches is guided to a, preferably near the core, heat exchanger area. This is ideally designed such that the highest possible surface is provided for heat exchange, for example by a cooling rib-like design. Of course, it is also conceivable to connect the Wärmeableitbleche with a heat sink.

Preferably, the heat is transferred from the heat exchanger area to the environment by means of natural convection. Of course, however, a forced cooling is conceivable.

The at least one heat dissipation sheet is arranged at least in sections between two adjacent layers of the ribbon-like amorphous core material and led out from at least one side surface of the amorphous transformer core or the amorphous transformer core disk. An amorphous transformer core is usually prefabricated from a plurality of layers of amorphous ribbon-like core material. This is to open in the manufacture of a transformer to arrange the transformer windings on formed from the strip material core legs. As mentioned above, an amorphous core sheet usually comprises a 360 ° rotation. The joints of the respective sheets are usually provided in one of the formed yokes, which also represents the respective opening point. When closing the transformer core or the transformer core disk packages of some 10 to 100 and more layers are mutually superimposed, so that in this process simply heat dissipating between the layer packages can be inserted.

The areal contacting of the respective heat dissipating plates with the adjacent layers of the ribbon-like amorphous core material ensures good heat transfer. Insofar as a material is used for the heat-dissipating plates, which has magnetic properties, and such heat-conducting plates are arranged in the joint area of respective layer pacts, any possible magnetic weak points of the amorphous core are compensated there in an advantageous manner. In order to reduce any eddy current losses in the heat sinks, it is possible to slit these or built in the form of several, mutually electrically isolated, adjacent strips. Their thermal conductivity is not significantly affected by this. Thus, an amorphous transformer core with improved heat dissipation from its interior is manufactured in a simple manner.

According to a further variant of the invention, the at least one heat dissipation sheet is angled on at least one side surface of the transformer core disk. This allows a space-saving guidance of the heat sinks to a likewise space-saving above the transformer provided heat exchange zone.

Following a particularly preferred variant of the transformer core according to the invention, the latter comprises at least two transformer core disks arranged parallel to one another and at least approximately congruent to one another, at least one heat dissipation sheet being arranged at least in sections between the adjacent transformer core disks. Transformer cores for higher power ratings, for example, in the range of 1 MVA and also significantly higher, are usually composed of several core disks due to the limited width of the available ribbon-like amorphous core material. In addition, the cooling problem and in particular an inhomogeneous temperature distribution are of particular importance here.

Ideally, heat sinks are disposed between two respective leg-like regions of adjacent transformer core disks. Usually, the transformer is arranged with the core in later operation. In this case, the core disks are arranged vertically, so that the interposed Wärmeableitbleche perpendicular and in a open above the transformer provided heat exchange zone. Of course, a transformer but also with lying amorphous core can be arranged. On the assumption of flat side surfaces of the transformer core disks, there is a surface heat transfer via the side surfaces of the ribbon-like amorphous strip material to the respective adjacent heat dissipation sheet.

In a further embodiment possibility of the amorphous transformer core according to the invention, this is mechanically stabilized by the at least one heat dissipation plate arranged between the congruently adjacent transformer core disks. For this purpose, it is necessary that the heat conduction has a certain thickness, for example 1 mm to 15mm, depending on the size and weight of the amorphous transformer core. Conventional Wärmeableitbleche can also be quite in the range of a thickness of 0.5mm and below. Thus, it is possible, for example, to provide a vertically arranged in a leg region Wärmeableitblech in the lower region with a transverse support plate, so that there is a T-shape. This would allow, for example, to support the respective adjacent transformer core disks from below on the crossbar thus formed. Likewise, however, it is readily conceivable to bond such a heat dissipation sheet to the adjacent side surfaces of the transformer core disks and to stabilize them in this way. For this purpose, it is preferable to use an adhesive with a high thermal conductivity, for example with an addition of boron nitride, which is an excellent conductor of heat. According to a further variant of the invention, it is also provided to provide a holding device in the upper region of the heat-dissipating plate, for example an eyelet, by means of which the transformer can be lifted by a crane or a similar lifting device. This simplifies the handling of the transformer core.

According to a further embodiment, a plurality of adjacent at least partially arranged Wärmeableitbleche are provided. The use of several Wärmeableitbleche allows on the one hand their homogeneous distribution as possible within the amorphous transformer core, which also a further homogenized temperature distribution is achieved during operation. Preferably, however, these sheets are to lead to a common heat exchange region above the transformer core, for which, in particular in the presence of multiple transformer core disks the area between the core discs offers that runs vertically upwards. In order to form a compact as possible strand, within which the heat dissipation plates are guided upwards, they are therefore to be guided parallel to each other.

Namely, according to a further variant of the invention, a common heat exchange region permits, in particular, simple forced cooling, for example by means of a blower or a heat exchanger. In this case, a single device is enough to cool the single heat exchange area.

To further increase the heat dissipation from the interior of the amorphous transformer core, it is provided to manufacture the at least one heat dissipation sheet mainly from the metal copper or aluminum, which are characterized by a particularly high thermal conductivity and also have a sufficiently high mechanical stability.

In particular, in the event that a respective heat sink is provided between a plurality of individual layers of the band-like amorphous material, it is proposed that this film-like, so perform particularly thin, for example, with a thickness of 50 .mu.m. This allows a particularly homogeneous heat dissipation from the interior of the amorphous transformer core. Insofar as the foil-like heat conducting sheets are provided with an electrical insulation layer, this advantageously further reduces possible eddy current losses, albeit already marginal in any case.

A further increase in the heat dissipation is inventively achieved in that the at least one heat dissipation sheet is provided in a flat contact surface area with the ribbon-like amorphous core material with a thermal paste or in that at least one heat sink in a flat contact surface area with the band-like amorphous core material by means of a preferably good thermally conductive adhesive is connected. In both cases, the heat transfer from the respective transformer core to the heat sink is improved in an advantageous manner.

The integration of at least one vertical cooling channel passing vertically through the transformer core, which is preferably integrated in a thigh-like region between adjacent transformer core disks, provides through the flow of a cooling medium, for example air, in combination with the heat dissipation plates for a particularly advantageous heat dissipation.

The above-mentioned advantages of the improved heat dissipation from inside the amorphous transformer core are also apparent, and in particular for a transformer comprising a transformer core according to one of claims 1 to 14, at least one hollow cylindrical electrical winding with a low and a high voltage side, wherein at least one leg-like pronounced region of the amorphous transformer core which engages through at least one winding in the hollow cylindrical interior and this is at least partially disposed in the at least one winding window. Due to the electrical operation of the windings, for example with a primary rated voltage of 20kV, a secondary rated voltage of 400V at a line frequency of 50Hz, takes place in the amorphous transformer core due to hysteresis losses, a heat input, which, however, is lower in a comparable conventional transformer core. This heat can then be conducted in a particularly effective manner with the heat sinks according to the invention from the interior of the transformer core, so that sets a lower and more homogeneous core temperature, which ultimately leads to improved magnetic operating properties of the amorphous core material.

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

eine exemplarische erste Transformatorkernscheibe in einer dreidimensionalen Ansicht,

Fig. 2

einen Schnitt durch einen ersten exemplarischen amorphen Transformatorkern,

Fig. 3

eine Seitenansicht auf einen zweiten exemplarischen Transformatorkern,

Fig. 4

eine Draufsicht auf einen dritten exemplarischen Transformatorkern mit Wicklungen sowie

Fig. 5

eine exemplarische zweite Kernscheibe.

Show it:

Fig. 1

an exemplary first transformer core in a three-dimensional view,

Fig. 2

a section through a first exemplary amorphous transformer core,

Fig. 3

a side view of a second exemplary transformer core,

Fig. 4

a plan view of a third exemplary transformer core with windings as well

Fig. 5

an exemplary second core disk.

Fig. 1 shows an exemplary first transformer core 10 in a three-dimensional view. A plurality of layers 12 of a band-like amorphous core material are arranged concentrically around two winding windows 14 and 16. Unlike the figure, however, several thousand of such layers are provided, each having a thickness in the range of, for example, 0.05mm to 0.1mm. The dimensions of the core may have a width in the range of 1.5m to 4m and a height of 1m to 2.5m and above, depending, of course, on the rated power to be achieved by a corresponding transformer, which may well be 10MVA and higher can. The width 18 of the transformer core depends essentially on the width of the available amorphous strip material and is limited to 20 cm, for example, due to the commercially available bandwidths and their high mechanical sensitivity. The core disk 10 is intended for a three-phase transformer with three windings, which is why in this case, due to the two winding windows 14, 16, three leg-like areas are provided, which are provided for receiving the three windings. Notwithstanding the drawings, the edges of the transformer core disc are not sharp-edged, but they are rather than assume round, for example, with an inner radius of curvature of 1 cm and an outer radius of curvature, which is slightly higher than a Schenlekbreite. This core design requires that ultimately three ring-like structures are formed of amorphous ribbon-like core material, namely one ring each around one of the two winding windows 14, 16 and a third outer ring, which surrounds the two inner rings. The joints of the respective layers are indicated in the lower yoke region, where the transformer core 10 can also be opened, for example, to arrange the transformer windings thereon. This would require the core disk be arranged hanging, but also quite mechanical support structures are conceivable, which allow an opening of the then reversed transformer core in the then upper yoke area.

Fig. 2 shows a section 20 through the first exemplary amorphous transformer core with two congruent adjacent arranged transformer core disks 32, 34. These are identically constructed and correspond approximately to that in the Fig. 1 shown transformer core, however, there are several Wärmeleitbleche 26 disposed between adjacent layers 24 and between several layers comprehensive layer packages. By the respective planar contact surfaces, a good heat transfer from the layers 22, 24 of the ribbon-like amorphous core material is ensured on the Wärmeableitbleche 26. However, this can be increased as needed by the use of a surface-distributed thermal compound. The even distribution of the heat sinks 26 within the transformer core disks 32, 34 allows a more homogeneous temperature distribution within the transformer core when in operation. Between the transformer core disks 32, 34, a channel-like region is formed, in which the heat dissipation plates 26 emerging laterally from the transformer core disks 32, 34 open and are angled upward. At the upper end of the channel-like region, the heat sinks exit from the transformer core and open into a heat exchange region 28. This is intended to deliver the heat energy to the environment, for example by means of natural convection. Of course, this area is also forcibly cooled, for example by ventilation, even with their already cooled air. To increase this effect, the ends of the Wärmeableitbleche 30 are bent up like a rib. An additional cooling effect occurs through the contact of the upwardly guided heat sinks with the inner side surfaces of the transformer core disks 32, 34, which in turn can be improved by the use of a thermal grease in any voids. Side plates 36, 38 are respectively provided on the two outer sides of the transformer core, which has two transformer core disks 32, 34. These serve primarily in this example, the mechanical stabilization of the transformer core and are, for example, at least partially glued to a respective side surface of a transformer core. Of course, it is possible to enhance their natural Wärmeableitfunktionalität thereby, that the side plates 36, 38 are extended into a lying outside of the actual transformer core heat exchange area.

Fig. 3 shows a side view 40 of a second exemplary transformer core. Again, the transformer core comprises two congruent adjacent transformer core plates 42, 44, wherein a channel-like region is formed between the two. Transversely through this area, and preferably between two thigh-like regions of the transformer core disks 42, 44, a plurality of heat dissipating plates 46 are provided parallel to each other, which completely fill the channel at least in the leg-like region, so that a good heat transfer from the respective areas of the side surfaces of the transformer core disks on the plan adjacent heat sinks 46 is ensured. Nevertheless, it is conceivable to improve the heat transfer through the use of a thermal compound. Likewise, it is also possible to perform the heat conducting plates 46 mechanically particularly stable, for example, with a thickness of 10mm, and these partially bonded to the transformer core plates 42, 44. On the one hand, this increases the stability of the transformer core disks 42, 44, which are inherently unstable due to the material, and also improves the heat dissipation when using an adhesive having a particularly high thermal conductivity. Such an adhesive can for example be based on an epoxy resin, to which a good heat-conductive filler such as boron nitride has been added. Due to drawing technology, only one vertically extending package of heat dissipating plates 46 is shown, but it can be assumed that a separate package of heat dissipating plates 46 is provided for each leg-like region. The Wärmeableitbleche 46 open in the upper and lower transformer core in a respective heat exchange region 50th

Fig. 4 shows a top view 60 of third exemplary transformer core with windings. This corresponds - apart from the changed perspective - essentially to the one in Fig. 3 shown transformer core. The transformer core comprises two congruent adjacent transformer core disks 62, 64, between which a gap is formed. In the yoke areas, heat-dissipating plates 66, 68 are arranged in a packet-like manner in this gap, which open into a respective heat exchange area 74. Within the respective leg areas, however, are additional cooling channels 70 are provided, which in turn provide for improved heat dissipation. Especially here it is advantageous if the cooling channels are forced through by a coolant. The contours of located on the respective core legs windings are indicated by the reference numeral 72. Of course, the use of three, four or more congruent adjacent transformer core is possible.

Fig. 5 10 shows an exemplary second transformer core disk 80 having four winding windows 82, 84, 86, 88 and concentric layers 92 of ribbon-like amorphous material disposed thereabout. There are three leg-like regions 92 indicated, which are provided for receiving a respective winding. The two outer leg-like regions are provided for the magnetic return, so that this shape resembles the shape of a five-limb core.

LIST OF REFERENCE NUMBERS

10

exemplary first transformer core disk

12

first layers of band-like amorphous core material

14

first winding window

16

second winding window

18

Width of the first transformer core

20

Section through the first exemplary amorphous transformer core

22

second layers of ribbon-like amorphous core material

24

adjacent layers of band-like amorphous core material

26

first heat sinks

28

first heat exchange area

30

Cooling fin-like ends of first heat sinks

32

first transformer core of first transformer core

34

second transformer core of first transformer core

36

first side plate of first transformer core

38

second side plate of first transformer core

40

Side view on second exemplary transformer core

42

first transformer core of second transformer core

44

second transformer core of second transformer core

46

second heat sinks

48

second heat exchange area

50

third heat exchange area

60

Top view of third exemplary transformer core with windings

62

first transformer core of third transformer core

64

second transformer core of third transformer core

66

Angled ends of third Wärmeableitblechen

68

third heat sink

70

cooling channels

72

windings

74

fourth heat exchange area

80

exemplary second core disk

82

third winding window

84

fourth winding window

86

fifth winding window

88

sixth winding window

90

third layers of band-like amorphous core material

92

thigh-like pronounced area

Claims (14)

1. Amorphous transformer core (20, 40, 60) comprising at least one transformer core disc (10, 32, 34, 42, 44, 62, 64, 80) with a multiplicity of layers of strip-like amorphous core material (12, 22, 24, 90) arranged concentrically around at least one winding window (14, 16, 82, 84, 86, 88), wherein at least one heat dissipating plate (26, 30, 46, 66, 68) extends into the interior of the amorphous transformer core (20, 40, 60) and wherein this is arranged at least in sections between two adjacent layers (24) of the strip-like amorphous core material, characterized in that the at least one heat dissipating plate (26, 30, 46, 66, 68) is fed out of at least one side surface of the amorphous transformer core (20, 40, 60) and is fed from there into at least one heat exchange region (28, 48, 50, 74) outside the amorphous transformer core (20, 40, 60), thus enabling an improved dissipation of heat energy which is produced inside the amorphous transformer core (20, 40, 60).
2. Amorphous transformer core according to Claim 1, characterized in that the at least one heat dissipating plate (26, 30, 46, 66, 68) is bent on the at least one side surface.
3. Amorphous transformer core according to Claim 1 or 2, characterized in that this comprises at least two transformer core discs (32, 34; 42, 44; 62, 64) which are arranged parallel and at least approximately congruently adjacent to one another, and that at least one heat dissipating plate (26, 30, 46, 66, 68) is arranged at least in sections between the adjacent transformer core discs (32, 34; 42, 44; 62, 64).
4. Amorphous transformer core according to Claim 3, characterized in that said core is mechanically stabilised by the at least one heat dissipating plate (26, 30, 46, 66, 68) arranged between the congruently adjacent transformer core discs (32, 34; 42, 44; 62, 64) .
5. Amorphous transformer core according to Claim 4, characterized in that the at least one heat dissipating plate (26, 30, 46, 66, 68) arranged between the congruently adjacent transformer core discs (32, 34; 42, 44; 62, 64) has a holding device in a heat exchange region (28, 48, 50, 74).
6. Amorphous transformer core according to one of the preceding claims, characterized in that a plurality of heat dissipating plates (26, 30, 46, 66, 68), which are arranged adjacently at least in sections, is provided.
7. Amorphous transformer core according to Claim 6, characterized in that a plurality of heat dissipating plates (26, 30, 46, 66, 68) is fed into a common heat exchange region (28, 48, 50, 74).
8. Amorphous transformer core according to one of the preceding claims, characterized in that at least one heat dissipating plate (26, 30, 46, 66, 68) is made predominantly from copper or aluminium.
9. Amorphous transformer core according to one of the preceding claims, characterized in that at least one heat dissipating plate (26, 30, 46, 66, 68) is designed in the form of a foil.
10. Amorphous transformer core according to one of the preceding claims, characterized in that at least one heat dissipating plate (26, 30, 46, 66, 68) is provided with a heat-conducting paste in a planar contact surface region with the strip-like amorphous core material (12, 22, 24, 90).
11. Amorphous transformer core according to one of the preceding claims, characterized in that at least one heat dissipating plate (26, 30, 46, 66, 68) is bonded to the strip-like amorphous core material (12, 22, 24, 90) in a planar contact surface region by means of an adhesive.
12. Amorphous transformer core according to one of Claims 3 to 11, characterized in that cooling channels (70) are formed between adjacent transformer core discs (32, 34; 42, 44; 62, 64).
13. Amorphous transformer core according to one of the preceding claims, characterized in that a cooling device is provided for the forced cooling of at least one heat exchange region (28, 48, 50, 74).
14. Transformer comprising

    • a transformer core (20, 40, 60) according to one of Claims 1 to 13,

    • at least one electrical winding (70) in the form of a hollow cylinder with a low-voltage and a high-voltage side, at least one limb-like region (92) of the amorphous transformer core (20, 40, 60) passing through the at least one winding (70) in the hollow-cylindrical interior, this being at least partially arranged in the at least one winding window (14, 16, 82, 84, 86, 88).

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