EP2916333A1 - Amorphous transformer core - Google Patents

Abstract

The invention relates to an amorphous transformer core (10) comprising a rectangle - like outer core ring (16) and two rectangular - like inner core rings (12, 14) each juxtaposed in a common plane into the outer core ring (16) each having a similar magnetic cross sectional area size, two in total Core yokes (26) and three core legs (20, 22, 24) are formed, whose respective magnetic total cross section in each case from the magnetic cross section (30, 70, 90, 110) of two different partially adjacent core rings (12, 14, 16) is formed wherein the core rings are wound around a respective winding axis (36, 50, 62, 76, 82, 96, 102, 118) from a plurality of winding layers (122) of amorphous ribbon material. The respective winding width of a winding layer of the amorphous strip material is increased in the case of the inner core rings (12, 14) with radially outer winding layers (122) with respect to radially inner winding layers (122) and in the case of the outer core ring (16) in the reverse manner, such that a respective at least approximately circular (30) or elliptical (70) magnetic total cross-section of at least the core limbs (20, 22, 24) is formed. The invention also relates to a transformer with a transformer core according to the invention.

Description

The invention relates to an amorphous transformer core, comprising a rectangular-like outer core ring and two adjacent in a common plane in the outer core ring rectangular-like inner core rings each having a similar magnetic cross-sectional area size, wherein a total of two core yokes and three core legs are formed, the respective magnetic total cross section respectively from the magnetic cross section of two different partially adjacent core rings is formed, wherein the core rings are wound around a respective winding axis of a plurality of winding layers of amorphous strip material.

It is well known that in electrical power distribution networks, for example in voltage levels of 6kV, 10kV, 30kV, 60kV or 110kV transformers are used to allow coupling between respective voltage levels. These typically include a transformer core and primary and secondary windings, with coupling being provided by a magnetic flux through the magnetic cross section of the transformer core.

A transformer core is usually constructed of layered core sheets, which are insulated from each other to prevent the formation of circular currents. Such transformer cores cause unwanted active losses during their operation, which lead to heating of the transformer core.

As a low-loss alternative to laminated transformer cores, wound transformer cores made of an amorphous strip material are known. This has a very small thickness of, for example, 25 microns, so that a plurality of turns is required to reach a magnetic thickness of the core cross-section, for example, 30cm. A known embodiment for a three-limbed transformer core of wound amorphous strip material is a so-called Evans core, in which two in a common plane adjacent inner wound core rings are nested in an outer wound core ring, so that form three core legs, the magnetic cross sections of each two magnetic cross sections of adjacent sections of adjacent core rings are formed.

A disadvantage here proves that the width of the magnetic cross section of a wound core ring is dependent on the width of the amorphous strip material used, which is for example a maximum of 30cm. There are therefore rectangular magnetic cross-sectional areas of the core rings, so that the resulting magnetic cross-sectional area of a core leg is also rectangular. The inner cross-section of hollow cylindrical coils arranged around a core leg is generally not rectangular for reasons of production technology, but rather approximately round or oval, so that the inner coil cross-section is not satisfactorily filled by a core leg with a rectangular magnetic cross-section arranged therein. The size of a corresponding transformer is thereby increased disadvantageously.

Based on this prior art, it is the object of the invention to provide an amorphous transformer core core core core, whose magnetic cross-sectional areas, at least in the core leg area allow a better fill factor. The task is also to provide a transformer with a corresponding transformer core.

This object is achieved by an amorphous transformer core of the aforementioned type. This is characterized in that the respective winding width of a winding layer of amorphous strip material increases in the case of the inner core rings with radially outer winding layers against radially inner winding layers and in the case of the outer core ring in the reverse Is reduced, so that a respective at least approximately circular or elliptical magnetic total cross-section of at least the core legs is formed.

The basic idea of the invention is to adapt the winding width of the respective winding layers in such a way that it increases with increasing radial distance from the winding axis in the inner core rings, so that the magnetic cross section increases in the radially outer direction and is semicircular in the theoretical ideal case. In the assembled state of the transformer core connects radially outside either a respective portion of the outer core ring or a portion of the adjacent inner core ring. Thus, advantageously, at least in the core leg regions, a roundish or elliptical overall magnetic cross section is achieved.

The term rectangle-like is to be interpreted broadly. The amorphous strip material is mechanically extremely sensitive and therefore usually a minimum bending radius is required, which should not be exceeded, in order to exclude breaking of the amorphous strip material. Such a minimum bending radius is for example in the range of greater than 0.5cm - 3cm, which may also cause a bending radius of 30cm and higher in radially outer layers, with a corresponding core ring shape according to the invention also be considered as a rectangle. On the other hand, at least in the region of the core limbs to be formed, it is also necessary to provide straight sections of the respective core rings so as to be able to arrange a hollow-cylindrical transformer coil or a winding with the highest possible fill factor.

The outer core ring according to the invention has an exactly opposite layering of the winding layers, so they are narrower with increasing radial distance, wherein the radially inner width of an outer core ring preferably corresponds to the radially outer width of an inner core ring. Thus, a stepless Ensures contiguity of the magnetic cross sections of radially outer and inner core rings. In an analogous manner, a comparable overall magnetic cross-sectional surface shape results in inner core rings adjoining one another in a plane.

In terms of production technology, it may prove expedient to separate a wound core ring after winding, so that a corresponding layer package is formed, which is joined together again during the production process to form a core ring. As a result, for example, a coil can be arranged around a section of an open core ring. According to the invention, such a cut and rejoined layer package is to be understood as a wound core ring.

According to the invention, an at least approximately circular or elliptical cross-section can expressly also be understood as a stepped cross-sectional shape, for example also a cross-sectional shape with only two steps, which can ultimately be assumed to be composed of three rectangular-like regions. Such a shape then has, for example, only two width variants of the winding layers, which is particularly easy to realize in terms of production technology.

Of course, the total magnetic cross section can be approximated by increasing the number of respective stages as close as possible to a circular upper elliptical overall cross section, or at exactly the inner cross section of a transformer coil which is to be arranged around a core leg thus formed. In such an embodiment, the amorphous strip material to be wound is continuously adjusted in its width along its extent, resulting in the shape of a very elongated wedge or trapezium for the strip material. A mechanical width adjustment is carried out for example by means of laser cutting the edges of an amorphous strip material of constant width.

According to a preferred embodiment of the amorphous transformer core according to the invention, a plurality of radially adjacent winding layers have at least one Kernringes the same width, thus step-like rectangular cross-sectional areas are formed. Several such superimposed winding layers are also referred to as layer packages. The number of widths of the winding layers used is thus reduced in an advantageous manner, which brings in particular production engineering advantages. Nevertheless, the achievable with such a cross-sectional shape filling factor of a core leg thus formed is advantageously increased.

According to a further embodiment of the transformer core according to the invention, at least one winding layer of a core ring is formed from at least two turns of the amorphous strip material arranged axially next to one another. In this way, the width of a winding layer can be varied in a particularly simple manner by using a corresponding number of adjacent turns or winding packages. This is particularly advantageous if the respective width of the turns or Windungslagenpakete is identical.

According to another variant of the invention, radially adjacent winding layers with axially adjacent turns of the amorphous strip material have an inner step-like axial offset from one another. Thus, radially superposed turns or winding packages overlap at their common interface, which advantageously leads to increased stability of the wound amorphous transformer core ring.

According to a further embodiment of the amorphous transformer core according to the invention, all windings of the amorphous strip material have the same width and are arranged in a common axial grid. This advantageously simplifies the production of a transformer core, in particular by using only a single bandwidth of the amorphous strip material.

According to a further variant of the invention of the amorphous transformer core, the width of the wound amorphous strip material is at least partially continuously adapted to a magnetic cross-sectional shape to be achieved. For this purpose, the width of the amorphous strip material to be wound, for example by means of laser cutting to modify the edges such that a core ring wound therefrom at least in regions has a desired magnetic cross-sectional shape with a correspondingly high filling factor. In this way, the actual magnetic cross section can be approximated arbitrarily close to the theoretical required cross section for a maximum fill factor.

According to a further embodiment of the amorphous transformer core according to the invention, cooling channels are provided at least in regions between adjoining core rings or adjoining winding layers. Amorphous core material increasingly loses its excellent magnetic properties when exceeding a threshold temperature. In order to ensure a desired low core loss even under heat-affected boundary conditions, for example when operating a transformer core in hot climates, cooling channels are optionally provided between at least two winding layers. These can be realized for example by strip-like elements, which are arranged for example on an insulating mat, which are wound as well as the amorphous strip material.

The advantages described above are also realized by a transformer comprising a three-limb transformer core according to the invention with at least one electrical winding around each of the three legs, wherein the inner diameter of the mostly hollow-cylindrical windings or coils is ideally adapted to the outer diameter of each transformer core leg of the transformer according to the invention , This results in a particularly high fill factor.

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 exemplarischen amorphen Transformatorkern,

Fig. 2

exemplarische Varianten von kreisförmigen magnetischen Querschnitten,

Fig. 3

exemplarische Varianten von elliptischen magnetischen Querschnitten,

Fig. 4

exemplarische Varianten von weiteren magnetischen Querschnitten,

Fig. 5

eine exemplarische Variante eines magnetischen Querschnitts mit Kühlkanal sowie

Fig. 6

einen Ausschnitt eines magnetischen Querschnitts eines Kernringes.

Show it:

Fig. 1

an exemplary amorphous transformer core,

Fig. 2

exemplary variants of circular magnetic cross-sections,

Fig. 3

exemplary variants of elliptical magnetic cross-sections,

Fig. 4

exemplary variants of further magnetic cross sections,

Fig. 5

an exemplary variant of a magnetic cross section with cooling channel and

Fig. 6

a section of a magnetic cross section of a core ring.

Fig. 1 shows an exemplary amorphous transformer core 10, which is also known under the name "Evans core". A first 12 and a second 14 rectangular-like core ring of wound amorphous ribbon material are disposed adjacent in a common plane. Both core rings 12, 14 are positively interlocked in a rectangular-like outer core ring 16 of wound amorphous ribbon material, which is arranged in the same plane. All winding axes of the core rings 12, 14, 16 are aligned parallel.

By such an arrangement, core shanks 20, 22, 24 and an upper and a lower yoke 26 are formed by partially adjacent core rings 12, 14, 16. The magnetic cross sections of the inner 12, 14 and the outer 16 core ring are at least approximately equal. Thus, the magnetic cross-section of the core legs 20, 22, 24 and the yokes 26 each results in twice the magnetic cross-section of a core ring 12, 14, 16. The middle core leg 22 is formed by adjacent portions of the inner core rings 12, 14 whereas the outer Core legs 20, 24 and upper and lower yoke 26 of adjacent regions of one of the inner core rings 12, 14 are formed with the outer core ring 16. It can not be deduced from this illustration that the magnetic cross sections of at least the core limbs 20, 22, 24 are roundish, which, however, is given in this case.

In the special form shown here, exemplary cooling channels 18 are arranged between adjoining core rings 12, 14, 16, which are approximately parallel to the Winding axes of the core rings 12, 14, 16 extend. Cooling channels 18 can be realized, for example, by inserting corresponding strips or cooling channel modules. Such a transformer core has, for example, a height of 1.5 m and a width of 2 m, and this information can vary greatly from case to case.

Fig. 2 Figure 14 shows exemplary variants of circular magnetic cross sections of core limbs in a drawing 30. Subvariante 30a shows an ideal semicircular magnetic cross section 32 of an inner core ring and an ideal semicircular magnetic cross section 34 of an outer core ring, both core rings being wound around a respective winding axis which is parallel to the winding axis represented by the reference numeral 36. In the nested state, the straight sections of the magnetic cross sections 32, 34 adjoin one another in regions and a core leg formed therefrom has a round overall cross section.

The example shown is, of course, also applicable in a comparable manner to a yoke cross-section or two sections of two inner core rings adjoining one another in the middle core leg.

The sub-variant 30b shows a stepped 42, 44, 46, 48 semicircular cross-section 38 of an inner core ring and a stepped semi-circular cross-section 40 of an outer core ring, wherein both core rings are wound around a respective winding axis, which is parallel to the winding axis represented by the reference numeral 50 , Here, the respective winding width of a winding layer or a winding package amorphous strip material is increased in the case of the inner core ring at radially outer winding layers against radially inner winding layers and reduced in the case of the outer core ring in the reverse manner.

Sub-variant 30c shows a stepped semicircular cross-section 52, comparable to sub-variant 30b, of an inner core ring with a plurality of windings 56, 58, 60 in the same winding layer, which is widened in the radial direction, and a corresponding stepped semicircular cross-section 54 of an outer core ring which is in Radial direction is narrowed. Both core rings are wound around a respective winding axis, which is parallel to the reference numeral 62 winding axis is shown. With a thickness of the amorphous strip material of, for example, 25 μm, the number of real winding layers can amount to several thousand, so that the turns 56, 58, 60 shown here can also be understood as winding layer packages each having a few hundred layers.

By using a plurality of turns 56, 58, 60 of amorphous strip material in the same winding layer, the number of widths of the amorphous strip material used can advantageously be reduced. In this example, radially adjacent winding layers with axially juxtaposed windings 56, 58, 60 of the amorphous strip material have an inner step-like axial offset from one another.

Fig. 3 FIG. 12 shows exemplary variants of elliptical magnetic cross sections in a drawing 70. Subvariante 70a shows an ideal semi-elliptical magnetic cross section 72 of an inner core ring and an ideal semi-elliptical magnetic cross section 74 of an outer core ring, both core rings being wound about a respective winding axis parallel to the inner core ring is the winding axis represented by the reference numeral 76. In the nested state, the straight sections of the magnetic cross sections adjoin each other in regions and an elliptical overall cross section of a core leg formed therefrom is reached.

Sub-variant 70b shows a stepped semi-elliptical magnetic cross-section 78 of an inner core ring and a stepped semi-elliptical magnetic cross-section 80 of an outer core ring, both core rings wound around a respective winding axis which is parallel to the winding axis indicated by reference numeral 82.

Fig. 4 10 shows exemplary variants of further magnetic cross sections in a representation 90. In sub-variant 90a, a first grid-shaped stepped semicircular cross-section 92 is shown by an inner core ring and a first grid-shaped stepped semicircular cross-section 94 from an outer core ring in relation to a winding axis 96.

In the case of the core rings in question, their magnetic cross section is not constant along their circumference. The cross-sections 92, 94 shown in sub-variant 90a lie in a respective leg region of a transformer core formed therefrom, in which at least approximately a roundish magnetic cross-section is to be achieved so that a hollow-cylindrical transformer coil or electrical winding can be arranged around a core leg formed therein with the highest possible fill factor ,

Sub-variant 90b shows a second grid-shaped stepped cross section 98 of an inner core ring and a second grid-shaped stepped cross section 100 of an outer core ring. The cross-sections 98, 100 shown in sub-variant 90b lie in a respective yoke region of a transformer core formed therefrom, in which the cross-sectional shape does not necessarily have to be round because there is no hollow-cylindrical transformer coil or electrical winding arranged there.

Due to the grid-shaped arrangement, a respective core ring is ultimately composed by a plurality of axially adjacent arranged partial core rings, which ideally each have the same axial width. As a result, the magnetic cross section of a core ring thus formed is not necessarily constant along its direction of rotation.

Fig. 5 11 shows an exemplary variant of a magnetic cross-section with a cooling channel in a representation 110. In sub-variant 110a, a first stepped semicircular cross-section 112 of an inner core ring and a first grid-shaped stepped semicircular cross-section 114 of an outer core ring in relation to a winding axis 118 are shown. Between two adjacent winding layers or ply packages respective cooling channels 116 are provided.

Fig. 6 shows in a representation 120 a section of the magnetic cross section of an exemplary core ring. Two rectangular cross-sectional areas are shown, which are formed as a respective layer package 124 of a plurality of winding layers 122 of an amorphous strip material.

LIST OF REFERENCE NUMBERS

10

exemplary amorphous transformer core

12

first rectangular-like inner core ring

14

second rectangle-like inner core ring

16

outer rectangle-like core ring

18

cooling channel

20

first core leg

22

second core leg

24

third core leg

26

lower core yoke

30

exemplary variants of circular magnetic cross sections

32

ideal semicircular cross section of inner core ring

34

ideal semicircular cross section of outer core ring

36

winding axis

38

stepped semi-circular cross section of inner core ring

40

stepped semi-circular cross section of outer core ring

42

first rectangular cross-sectional area

44

second rectangular cross-sectional area

46

third rectangular cross-sectional area

48

fourth rectangular cross-sectional area

50

winding axis

52

stepped semi-circular cross-section of inner core ring with several turns in self-winding layer

54

stepped semi-circular cross-section of outer core ring with several turns in self-winding layer

56

first turn of winding layer

58

second turn of winding layer

60

third turn of winding layer

62

winding axis

70

exemplary variants of elliptical magnetic cross sections

72

ideal elliptical cross section of inner core ring

74

ideal elliptical cross section of outer core ring

76

winding axis

78

stepped elliptical cross section of inner core ring

80

stepped elliptical cross section of outer core ring

82

winding axis

90

exemplary variants of further magnetic cross sections

92

first grid-shaped stepped semicircular cross-section of inner core ring

94

first grid-shaped stepped semicircular cross-section of outer core ring

96

winding axis

98

second grid-shaped stepped semicircular cross-section of inner core ring

100

second grid-shaped stepped semicircular cross section of outer core ring

102

winding axis

110

exemplary variant of a magnetic cross section with cooling channel

112

stepped semi-circular cross section of inner core ring with cooling channel

114

stepped semi-circular cross section of outer core ring with cooling channel

116

cooling channel

118

winding axis

120

Detail of magnetic cross section of a core ring

122

Winding layers of a layer package

124

rectangular cross-sectional area

Claims (9)

Amorphous transformer core (10) comprising a rectangular-like outer core ring (16) and two in a common plane adjacent in the outer core ring (16) interlaced rectangular-like inner core rings (12, 14) each having a similar magnetic cross-sectional area size, wherein a total of two Kernjoche (26) and three core limbs (20, 22, 24) are formed, the respective magnetic total cross section of each of the magnetic cross section (30, 70, 90, 110) of two different partially adjacent core rings (12, 14, 16) is formed, wherein the core rings about a respective winding axis (36, 50, 62, 76, 82, 96, 102, 118) are wound from a plurality of winding layers (122) of amorphous strip material,
characterized,
that the respective winding width of a winding layer of amorphous strip material in the case of the inner core rings (12, 14) is increased with radially outer winding layers (122) compared to radially inner winding layers (122) and in the case of the outer core ring (16) is reduced in the reverse manner, such that a respective at least approximately circular (30) or elliptical (70) magnetic total cross-section of at least the core limbs (20, 22, 24) is formed. Amorphous transformer core according to claim 1, characterized in that a plurality of radially adjacent winding layers (122) of at least one core ring (12, 14, 16) have the same width and thus step-like rectangular cross-sectional areas (42, 44, 46, 48, 124) are formed. Amorphous transformer core according to claim 1 or 2, characterized in that at least one winding layer (122) of a core ring (12, 14, 16) of at least two axially juxtaposed windings (56, 58, 60) of the amorphous strip material is formed. Amorphous transformer core according to claim 3, characterized in that radially adjacent winding layers (122) having axially juxtaposed windings (56, 58, 60) of the amorphous strip material have an inner step-like axial offset from each other. Amorphous transformer core according to claim 3, characterized in that all the turns of the amorphous strip material have the same width and are arranged in a common axial grid. Amorphous transformer core according to one of the preceding claims, characterized in that the width of the wound amorphous strip material is at least partially continuously adapted to a magnetic cross-sectional shape to be achieved. Amorphous transformer core according to one of the preceding claims, characterized in that at least partially cooling channels (18, 116) are provided between adjoining core rings (12, 14, 16). Amorphous transformer core according to one of the preceding claims, characterized in that at least partially cooling channels (18, 116) are provided between adjoining winding layers (124). A transformer comprising a three-leg transformer core having at least one electrical winding each of the three core legs, characterized in that the transformer core is a transformer core (10) according to one of claims 1 to 8.

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