EP2975618B1 - Core for an electrical induction device - Google Patents

Description

The invention relates to a core for an electrical induction device with a plurality of laminated cores, each formed by laminated sheets, wherein the laminated cores are parallel to the layer plane of the laminated sheets to each other, wherein at least one of the laminated cores is segmented and has at least two partial laminated cores, the two Partial laminated cores each with their sheet metal end faces, which are transversely, in particular perpendicularly, to the layer plane of the laminated sheets, face each other, the sheet metal end faces of the two partial laminated cores have a distance from each other through which a perpendicular to the layer plane extending gap between the two partial laminated cores is formed and the Gap forms a cooling channel or at least a portion of a cooling channel whose channel longitudinal direction extends transversely, in particular perpendicular, to the layer plane of the laminated sheets.

Such a ker is from the US 2991437 A already known. The core shown there has legs, which are formed from stacked sheets. Each laminated core is subdivided into two partial laminated cores, which form sheet metal end faces that run transversely to the layer plane of the laminated metal sheets. In a cross-sectional view, these end faces are arranged at a distance from each other and delimit a cooling channel, which has a larger diameter in the interior than in its outer edge regions. In addition, a further cooling channel is provided whose channel longitudinal direction extends parallel to the layer plane of the laminated sheets. The disadvantage, however, is that the mechanical production of the core is complicated and expensive.

The FR 573664 A also discloses a core whose legs define internal cooling channels. Again, the production of the core is costly.

From the state of the art, laminated cores are known from sheets (also called magnetic sheets or core sheets), these are also called stack cores. Such cores can be performed by cutting different width sheets, graded for each individual laminated core. Furthermore, cores (also called band cores) are known in which the sheet is wound coil-shaped largely uninterrupted.

The material used for the sheets mainly grain-oriented, cold-rolled sheet is used, which has a magnetic preferred direction in the rolling direction. Due to the layering of the core from these grain-oriented sheets, the heat resulting from the no-load losses is dissipated to and across the layer plane at different extents from the surface. This is expressed in a usually by the factor 6 ... 7 different thermal conductivity.

At present, cooling ducts are used parallel to the layer plane in transformer construction, since they can be easily formed by inserting strips or spacers (for example, ceramic disks). A disadvantage of this cooling channel formation is that the arrangement of the cooling channels can not exploit the favorable heat conduction parallel to the layer direction of the sheets.

Also, special external cooling surfaces for cooling cores are known; such are for example in the German patent specification DE 35 05 120 described.

To further reduce the no-load losses now increasingly amorphous core materials are used in distribution transformers. The state of the art with regard to the use of amorphous core material is disclosed, for example, in the European published patent application EP 2 474 985 and Japanese Patent Publication JP 2010 289 858 described.

Due to the high material costs for amorphous core materials, the difficult processing as well as the restricted design options, amorphous materials, especially for larger power transformers, have not yet been able to assert themselves.

The invention has for its object to provide a core of the type mentioned, which is inexpensive to produce and ensures a sufficiently good heat dissipation.

This object is achieved in that the width of the sheets of laminated cores is different with the formation of steps between stacked laminated cores, the number of different sheet widths in the partial laminated cores is a maximum of one third of the number of stages.

Thereafter, the invention provides that at least one of the laminated cores is segmented and has at least two partial laminated cores, each with their sheet metal end faces, which are transversely, in particular perpendicular to the layer plane of the laminated sheets, face each other, the sheet metal end faces of the two partial laminated cores a distance have to each other through which a gap extending perpendicular to the layer plane between the two partial laminated cores is formed and the gap forms a cooling channel or at least a portion of a cooling channel whose channel longitudinal direction extends transversely, in particular perpendicular, to the layer plane of the laminated sheets.

An essential advantage of the core according to the invention is that the good thermal longitudinal conductivity of the sheets is used for cooling the core by the described arrangement of the cooling channels or transverse to the layer plane of the sheets. As a result, it is advantageously possible to achieve a reduction in the space requirement required for cooling and an increase in the filling factor for the core limb.

A further significant advantage of the core according to the invention is the fact that the described formation of the core of partial laminated cores is suitable both for cores layered from individual sheets and for cores wound from magnetic tapes.

According to the invention, the width of the laminations of the laminations is different to form steps between stacked laminations.

The number of different sheet widths in the partial laminated cores is a maximum of one third of the number of stages. Preferably, the number of different sheet widths in the partial laminated cores is a maximum of three. In this way, the core can be cut easily and thus inexpensively.

It is advantageous if, due to the step formation, the cross section of the core is adapted at least in sections to a circular cross section.

The sheet widths in the partial laminated cores are preferably identical.

It is also considered to be advantageous if at least two stacked laminated cores have an identical number of equally wide partial laminated cores but are nevertheless of different widths, wherein at least two partial corrugated iron packages are separated from one another by the or one of the cooling channels in the case of the broader laminated core.

A particularly preferred embodiment provides that the core viewed from the inside out alternately comprises a laminated core of the first type and a laminated core of the second type, wherein in a laminated core of the first kind at least two partial laminated cores, preferably all partial laminated cores, are separated from each other by a gap or cooling channel, and being at one Laminated core of the second kind, at least two partial laminated cores, preferably all partial laminated cores, lying gap-free on each other.

Preferably, at least two stacked laminated cores of the first and second type have the same number of equally wide partial laminated cores.

It is also advantageous if the sheets are formed by a thin-walled strip material, preferably an amorphous strip material, and the laminated cores are each wound from this strip material.

For further cooling, at least one cooling channel is preferably additionally present whose channel longitudinal direction extends parallel to the layer plane of the laminated sheets.

A further preferred embodiment provides that the laminated cores are bent in sections, wherein the bending radii of at least two stacked laminated cores are selected such that in the bending region between these laminated cores, a cavity, preferably in the form of an arcuate gap, is formed, wherein the cavity with a the cooling channels or all the cooling channels communicates and allows feeding of a coolant through the cavity into the one or more cooling channels.

The width of the widest partial laminated core is preferably an integer multiple of the narrowest partial laminated core.

Tension bands are preferably used for the mechanical stabilization. Accordingly, it is provided in a further preferred embodiment of the core, that the wound partial laminated cores are stabilized and fixed by means of clamping bands, wherein the clamping bands are arranged on the laminated cores, that they each in their position to the clamping band of adjacent partial laminated core are offset and are designed such that forms a cooling channel in the space between the partial laminated cores. For cost reasons, straps made of metallic non-magnetic material are preferably used.

When using the core in throttles air gaps can be provided, which are glued to the core material.

Particularly advantageous is the above-described gradation of the core in cores made of amorphous or nanocrystalline strip material, since the use of round short-circuit resistant windings is made possible.

In order to easily control the radial winding forces occurring in the event of a short circuit, windings with circular coils which are placed on the limbs of the core are preferred for transformers and chokes.

In order to achieve a high filling factor for the core limb (optimum filling of the circular cross-section of the winding with magnetic material), the cross-section of the limb is preferably stepped several times.

A further advantageous embodiment of the core provides for the formation of core stages from the laminated cores and thus an approximation to the circular shape of the winding when using core sheets only one or less sheet widths. At the same time the formation of effective and space-saving cooling channels is made possible.

As can be seen from the above explanations, the preferred core configurations are also suitable for cores of electrical induction devices which operate in the high-frequency range, since the above-mentioned advantages due to the frequency dependency of the magnetic reversal losses in these preferably come into effect and the application even with relatively small benefits offers economic benefits.

In a preferred embodiment, the bending radii of the wound partial laminated core of a composite core are each selected such that in each case a gap is formed for the circulation of a cooling fluid in the arc between leg and yoke. In this case, the lower sheet for receiving the cooling fluid, which flows transversely to the winding direction, is distributed within the arc on the cooling channels between the partial laminated cores to then ascend by the heating and exit at the upper arc between leg and yoke again.

The invention will be explained in more detail with reference to preferred embodiments, these are in the FIGS. 1 to 16 shown in more detail.

For the sake of clarity, the same reference numerals are always used in the figures for identical or comparable components.

The FIG. 1 shows an example of a core 1 for an electromagnetic induction device, not shown. The core 1 consists of a plurality of laminated cores 2, which are each formed by laminated sheets 11 of magnetizable material, wherein the laminated cores are parallel to the layer plane of the laminated sheets 11 to each other.

In the example, at least part of the laminated cores 2 is segmented and has a plurality of partial laminated cores 3. The partial laminated cores 3 are at least partially arranged such that at the joint between the sheet metal end faces 3a of the partial laminated cores a gap results, which is dimensioned such that the flow of a coolant allows and a cooling channel 4 is formed.

In the case of a laminated core with a rectangular cross-section, neutral planes with the highest temperature are established, which are each perpendicular to the direction of the considered heat flow and intersect the package axes. Starting from them, the core temperature drops parabolic down to the core surface to drop there within the flow zone of the coolant to the amount of oil temperature. The heat flux density at the core surface is largely dependent on the internal thermal resistance of the body. This is significantly smaller in the layer plane than across it. The losses, however, are largely evenly distributed on the sheet metal body. With the cooling channels 4 perpendicular to the layer plane thus a particularly effective cooling can be achieved. As a result of the possible reduction of the cross-sectional requirement for the cooling channels 4, an increase of the filling factor of the iron circle and thus a reduction of the core cross-section can be achieved.

By the number of partial laminated cores 3, the total width of the individual laminated cores 2 is determined in each case. The height of the laminated cores 2 is adjusted by the number of layered sheets 11. By appropriate selection of the mentioned parameters, a stepped core is formed. In the example according to FIG. 1 all core lamination packages 2 are formed from core sheet metal stiffeners or partial lamination stacks 3 of the same width.

In the example according to FIG. 1 the partial laminated cores 3 are each arranged alternately with or without a gap, that is, with or without cooling channels between the partial laminated cores 3. This results in a different overall width of the laminations 2 forming the steps of the core 1.

In the example according to FIG. 1 Every second laminated core has cooling channels 4, so that the number of stages doubles again, without the need for additional sheet metal widths. In this way it is possible to achieve a substantial approximation of a core leg to a circular shape. Thus The use of round windings with high filling factor of the core is possible without the use of a variety of different sheet widths.

The FIG. 2 shows in a plan view the sectional view of a laminated from magnetic sheets leg 6 of another example of a core 1. The leg 6 and connected thereto yoke 7 are stacked in this example of individual sheets. The individual sheets form in the transition region between the legs and yoke joints, which are offset in layers against each other and form a tapping.

The illustrated segmentation of the laminated cores 2 in partial sheet metal paks 3 and the possible arrangement of the cooling channels 4 at the cutting edges of the sheet, the use of high thermal longitudinal conductivity of the sheets 11 is possible.

The illustrated arrangement of the cooling channels 4 along the cut edges of the sheets 11 not only a good thermal conductivity of the sheets 11 is used transversely to the layer plane, but it can continue to use targeted cooling channels in the thermally highly stressed areas of the core.

In the example according to FIG. 2 is the central core forming sheet package with three cooling channels 4 and the second core stage with a single cooling channel 4 is provided. Cooling channels in the already well cooled edge layers of the core 1 can be omitted, and a further increase in the filling factor of the core 1 is possible.

The FIG. 3 shows an embodiment in which a five-stage core 1 using two different widths for the sheets 11.1 and 11.2 of the partial laminated cores 3 is executed. As a result, it is possible to form a finely graded core of high number of stages with only two different sheet widths of the core material.

In the in the FIG. 3 illustrated embodiment, the width of the largest partial laminated core 3 forms a multiple of the smallest width of a partial laminated core. Due to the aforementioned formation of multiples of the width of the partial laminated cores 3, the formation of connections between the cooling channels 4 of the successive laminated cores is simplified. In the embodiment according to FIG. 3 are provided by this design all stages with cooling channels 4, which are connected to each other such that a cooling medium can flow transversely to the laminar layer direction of the sheets 11.1 and 11.2.

The FIG. 4 shows another example; In this, the laminated sheets 11 of the laminated cores 2 are formed by means of a wound strip material. This example lends itself, for example, to sheets with a preferred magnetic direction, since the sheet is obtained in strip form and can be wound without interruption. In order to set up the electrical windings, the individual turns of the ribbon core are separated so staggered that in each case only one point of application lies in the magnetic circuit. This wound core design is particularly suitable for the use of strips of amorphous core material or strips of nanocrystalline metals.

The layering of the winding layers is in the FIG. 4 shown in the sectional view of the leg 6. You can see that here only strip material of a width is used. The strip material is continuous, each comprising two legs 6 and the yokes 7, wound. The composition of the middle laminated cores from a plurality of partial laminated cores 3 creates a stepped core, which is adapted to the circular shape 8.

As can be seen, the laminated cores, which form the central core stage, each provided with transverse to the layer plane cooling channels 4.

The FIG. 5 FIG. 4 shows a three-dimensional sectional view of the three-limb core wound from strip material. The strip material is wound circumferentially to form the cooling channels 4 designed as described above, each in partial laminated cores 3, which respectively form corresponding legs 6 and yoke sections 7. In the embodiment according to FIG. 5 the cooling channels 4 of the core legs 6 are continued in the yokes 7 of the core.

The FIG. 6 shows the full view of an embodiment of the active part of a three-phase transformer, which is provided with a cooling channels 43 provided with core 1. On the legs 6 windings 9 of the three-phase transformer are arranged in the embodiment. The partial laminated core of the core 1 are formed in the embodiment of amorphous strip material.

The FIG. 7 shows a sectional view of the in FIG. 6 shown embodiment in more detail. In the exemplary embodiment, the bending radii 17 of the mutually stacked laminated core 3 of a composite core 1 are each selected such that in the arc between leg 6 and yoke 7 each arcuate gap 23 and thus a cooling channel 43 is formed for the circulation of a cooling fluid.

The FIG. 8 shows a section through the leg 6 of another example of a core 1, in which the partial laminated cores 3 of the metal sheets 2 are produced by means of a wound strip material. The seven-stage core shown in the example uses only plates 11 of a single bandwidth to form the steps.

In the background, the lower yoke 7 of the core 1 is seen in full view. The strip material is continuous, each comprising two legs 6 and the yokes 7, wound.

The FIG. 9 shows the core 1 according to FIG. 8 in a three-dimensional view obliquely from the side.

The FIG. 10 shows a sectional view through the axis of the central limb of another embodiment of a three-limb core parallel to the plane of the core band. Between the partial laminated cores 3 of the leg 6 vertical cooling channels 4 are arranged.

In the embodiment according to FIG. 10 the winding radii 17 of the partial laminated core 3 of the core 1 are each chosen such that in the arc between leg 6 and yoke 7 each have a curved gap 23 is formed to form a cooling channel 43 for the circulation of the coolant. This arcuate gap 23 is connected to the cooling channels 4 between the partial laminated cores 3. In this case, the lower sheet for receiving the coolant, which flows transversely to the winding direction, is distributed within the arc on the cooling channels 43 between the bands to then ascend by the heating and exit at the upper arc between leg 6 and yoke 7 again.

The FIG. 11 shows a partial view of the leg-yoke transition of in FIG. 10 described embodiment in more detail.

The FIG. 12 shows the front view of an embodiment with wound ribbon core of amorphous material, in which the laminations 2 are radially spaced from each other by means of inserts 48 such that a cooling channel 42 for supplying the cooling channels (not visible) is formed between the mutually parallel partial laminated cores.

The FIG. 13 shows an embodiment of the center leg 6 of a three-phase transformer, each with a plurality of the center leg 6 with a neighboring leg magnetically coupling partial laminated cores. It can be seen in the region of the associated with the yoke 7 leg 6 radial cooling channels 42 between the partial laminated cores. For the mechanical Stabilizing clamping bands 52 are used, which include the partial laminated cores at the periphery. These can be arranged both transversely and longitudinally to the winding direction. In the embodiment according to FIG. 13 the arrangement is longitudinal, ie parallel to the winding direction.

The clamping bands 52 are preferably positioned in the transverse direction on the partial laminated cores in such a way that they are offset in their position relative to the clamping band of the adjacent partial laminated core and the space between the partial laminated cores forms a cooling channel.

The FIG. 14 shows a three-dimensional view of the three-limb core according to FIG. 13 ,

The FIGS. 15 and 16 show an embodiment of a five-limb core. In this case, the core is preferably formed from wound partial laminated cores of a strip material.

The three inner legs are provided for mounting windings, while the outer serve as a return leg. Again, the cores are made of wound segments of preferably amorphous strip material.

Claims (12)

1. Core (1) for an electrical induction device comprising a large number of lamination stacks (2) which are each formed by laminated sheets (11, 11.1, 11.2), wherein the lamination stacks (2) lie one on the other parallel to the layer plane of the laminated sheets (11, 11.1, 11.2), wherein

   - at least one of the lamination stacks (2) is segmented and has at least two partial lamination stacks (3),

   - the two partial lamination stacks (3) lie opposite one another in each case by way of their lamination end sides (3a) which are transverse, in particular perpendicular, to the layer plane of the laminated sheets (11, 11.1, 11.2),

   - the lamination end sides (3a) of the two partial lamination stacks (3) are at a distance from one another, a gap, which extends perpendicular to the layer plane, between the two partial lamination stacks (3) being formed by said distance, and

   - the gap forms a cooling channel (4) or at least a section of a cooling channel (4), the longitudinal direction of said cooling channel extending transverse, in particular perpendicular, to the layer plane of the laminated sheets (11, 11.1, 11.2),

   characterized in that
   the width of the laminations (11, 11.1, 11.2) of the lamination stacks (2) is different, so as to form steps between lamination stacks (2) which lie one on the other, the number of different lamination widths in the partial lamination stacks (3) is at most one third of the number of steps.
2. Core (1) according to Claim 1,
   characterized in that
   the cross section of the core (1) is matched to a circular cross section at least in sections owing to the formation of steps.
3. Core (1) according to one of the preceding claims,
   characterized in that
   the number of different lamination widths in the partial lamination stacks (3) is at most three.
4. Core (1) according to one of the preceding claims,
   characterized in that
   the lamination widths in the partial lamination stacks (3) are identical.
5. Core (1) according to one of the preceding claims, characterized in that

   - at least two lamination stacks (2) which are situated one on the other have an identical number of partial lamination stacks (3) of identical width, but are nevertheless of different width,

   - wherein, in the case of the relatively wide lamination stack (2), at least two partial lamination stacks (3) are separated from one another by the or one of the cooling channels (4).
6. Core (1) according to one of the preceding claims,
   characterized in that

   - the core (1), as viewed from the inside to the outside, alternately has a lamination stack of the first kind and a lamination stack of the second kind.

   - wherein, in the case of a lamination stack of the first kind, at least two partial lamination stacks (3), preferably all of the partial lamination stacks (3), are separated from one another by a gap or cooling channel (4), and

   - wherein, in the case of a lamination stack of the second kind, at least two partial lamination stacks (3), preferably all of the partial lamination stacks (3), lie one on the other without a gap.
7. Core (1) according to Claim 6,
   characterized in that
   at least two lamination stacks (2) of the first and second kind which lie one on the other have the same number of partial lamination stacks (3) of identical width.
8. Core (1) according to one of the preceding claims,
   characterized in that

   - the laminations (11, 11.1, 11.2) are formed by a thin-walled strip material, preferably an amorphous strip material, and

   - the lamination stacks (2) are each wound from this strip material.
9. Core (1) according to one of the preceding claims,
   characterized in that
   there is additionally at least one cooling channel (4), the longitudinal direction of said cooling channel extending parallel to the layer plane of the laminated sheets (11, 11.1, 11.2).
10. Core (1) according to one of the preceding claims,
    characterized in that

    - the lamination stacks (2) are bent in sections, wherein the bending radii of at least two lamination stacks (2) which lie one on the other are selected in such a way that a hollow space, in particular in the form of an arcuate gap (23), is formed in the bending region between these lamination stacks (2),

    - wherein the hollow space is connected to one of the cooling channels (4) or all of the cooling channels and makes it possible for a coolant to be fed into the cooling channel or cooling channels (4) through the hollow space.
11. Core (1) according to one of the preceding claims,
    characterized in that
    the width of the widest partial lamination stack is an integer multiple of the narrowest partial lamination stack.
12. Core (1) according to Claim 8,
    characterized in that

    - the wound partial lamination stacks (3) are stabilized and fixed by means of tensioning belts (52),

    - wherein the tensioning belts (52) are arranged on the lamination stacks (2) in such a way that the position of said tensioning belts is respectively offset in relation to the tensioning belt of the adjacent partial lamination stack (3) and said tensioning belts are designed in such a way that a cooling channel (4) is formed in the space between the partial lamination stacks (3).

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