Transformer

Abstract

The invention relates to a transformer (1), in particular to a medium-frequency transformer, comprising a transformer core (2) having a plurality of core limbs (4) interconnected by means of yokes (3), and at least two conductor assemblies (5, 6) which are arranged around at least one of the core limbs (4), characterized in that each conductor assembly (5, 6) is in the form of a lamination stack having multiple laminations (7) arranged one above the other in a stacking direction.

Description

[0001] Description

[0002] Transformer

[0003] The invention relates to a transformer, in particular a medium-frequency transformer, comprising a transformer core with a plurality of core limbs connected to one another via yokes, and at least two conductor arrangements arranged around at least one of the core limbs. In particular, the invention relates to a medium-frequency transformer designed for frequencies from 100 Hz to several 1 kHz.

[0004] Transformers are known in the state of the art in a wide variety of designs. It is also known to design transformers for higher frequencies in order to reduce their size. For example, medium-frequency transformers require a transformer core with core limbs of a significantly smaller cross-section for comparable power transmission compared to conventional transformers operated at the usual mains frequency of 50 Hz. However, this does not apply to the conductors of the conductor arrangements designed as windings, which must transmit the load current. Accordingly, winding a winding wire with a comparatively large cross-section around a core limb with a comparatively small cross-section poses manufacturing problems.

[0005] Based on this prior art, it is an object of the present invention to provide a transformer of the type mentioned at the outset with an alternative structure. To achieve this object, the present invention provides a transformer, in particular a medium-frequency transformer, comprising a transformer core with a plurality of core limbs that are connected to one another via yokes, and at least two conductor arrangements that are arranged around at least one of the core limbs, characterized in that each conductor arrangement is designed as a laminated lamination stack with a plurality of laminated laminations arranged one above the other in a stacking direction, which laminated laminations can be made in particular from copper or aluminum.Thanks to this design, the conductor arrangements can be manufactured by stacking individual sheet metal laminations around the corresponding core leg, thus eliminating the traditional winding process and significantly simplifying production, particularly with comparatively small core leg cross-sections, as occurs in medium-frequency transformers.

[0006] According to one embodiment of the present invention, the sheet metal laminations have an electrically insulating coating, for example a thin layer of lacquer or enamel, in order to prevent a short circuit.

[0007] Preferably, the laminations are each U-shaped, which allows them to be stacked around the associated core leg particularly easily and in a space-saving manner. The laminations are stacked in particular such that at least one stack formed from main laminations, when the core leg is viewed from above, also has a U-shape.

[0008] Advantageously, the laminations are each formed from a plurality of lamination strips arranged adjacent to one another in a direction transverse to the stacking direction and preferably U-shaped. Thanks to the slots then present between adjacent lamination strips of a lamination, eddy current losses can be reduced.

[0009] The lamination stack of at least one conductor arrangement preferably has main laminations and counter laminations which are electrically connected to one another, the counter laminations having a shorter length than the main laminations. The main laminations are each guided around the associated core leg, while the counter laminations are positioned such that they are not interlinked with the magnetic flux through the transformer core. By providing such counter laminations, eddy current losses can be reduced and stray inductances can be adjusted. In addition, a plurality of adjacently arranged main laminations can be electrically connected to one another via counter laminations in such a way that these main laminations are electrically connected in series across the stack depth and have current flowing through them in the same direction, via which the length of the conductor can be adjusted.Thus, the main laminations of the high-voltage conductor arrangement are advantageously connected in series via counter laminations, in particular all main laminations of the high-voltage conductor arrangement.

[0010] In at least one conductor arrangement, in particular in the low-voltage conductor arrangement, sheet metal laminations, in particular all main sheet metal laminations, are electrically connected in parallel in the stacking direction.

[0011] According to one embodiment of the present invention, the transformer is characterized in that the transformer core has at least three adjacently arranged core legs, that at least two high-voltage windings and at least two low-voltage windings are arranged on the middle transformer core leg, that the at least two high-voltage windings are positioned between the low-voltage windings, and that the laminations of the high-voltage winding are connected in series in the stacking direction and laminations of the low-voltage windings, in particular all laminations of the low-voltage windings are connected in parallel in the stacking direction.

[0012] Further advantages and features of the present invention will become apparent from the following description with reference to the accompanying drawings.

[0013] Figure 1 is a sectional schematic plan view of a transformer according to an embodiment of the present invention;

[0014] Figure 2 is a sectional schematic side view of the transformer shown in Figure 1;

[0015] Figure 3 is a schematic perspective exploded view of a portion of a transformer winding of the transformer shown in Figure 1; and

[0016] Figure 4 is a sectional schematic plan view of a main sheet metal lamination according to a further embodiment of the present invention.

[0017] Figures 1 to 3 show a transformer 1 according to an embodiment of the present invention and components thereof. The transformer 1 in the present case is a medium-frequency transformer which can be designed for frequencies from 100 Hz up to a few 1 kHz. It comprises a laminated transformer core 2 made of steel with three core limbs 4 connected via yokes 3, the cross-section of the middle core limb 4 being selected to be twice as large as the cross-section of the two outer core limbs 4. The transformer 1 also comprises four conductor assemblies 5, 6 which are arranged one above the other around the middle core limb 4 and are insulated in the direction of the transformer core 2, for example by insulation sleeves (not shown in detail). The two middle conductor assemblies 5 in the present case serve as high-voltage conductor assemblies and the two outer conductor assemblies 6 as low-voltage conductor assemblies.Each conductor arrangement 5, 6 is provided as a lamination stack with a large number of U-shaped laminations 7 arranged one above the other in a stacking direction, which in this case are made of copper or aluminum and provided with an electrically insulating coating, for example of varnish or enamel. The laminations 7 of the high-voltage conductor arrangements 5 are electrically connected in series and the laminations 7 of the low-voltage conductor arrangements 6 are connected in parallel. The high-voltage conductor arrangements 5 each have, as shown in Figure 3, U-shaped main laminations 7.1 and counter laminations 7.2 for the technical implementation of the series connection, the length of the counter laminations 7.2 being selected to be shorter than the length of the main laminations 7.1.

[0018] Each counter lamination 7.2 is electrically connected at one of its free ends to the main lamination 7.1 arranged above it and at the other free end to the main lamination 7.1 arranged below it, for which purpose corresponding contact surfaces 8 are formed on the main and counter laminations 7.1 and 7.2, the downward-facing contact surfaces 8 being shown hatched in Figure 3. Accordingly, the counter laminations 7.2 reverse the current flow during transformer operation without interlinking with the core flux, as indicated in Figure 3 by the arrows 9, which means that current flows through all of the main laminations 7.1 in the same direction. In addition, the counter laminations 7.2 reduce the stray flux between the two main arms of the main laminations 7.1. This means that the stray inductance can also be controlled via the length of the counter-lamellae 7 . 2 .In addition, eddy current losses are also reduced.

[0019] It should be noted that the illustrated circuit of high-voltage and low-voltage conductor arrangements 5, 6 can also be multiplied. Furthermore, a different arrangement of the high-voltage and low-voltage conductor arrangements 5, 6 can naturally also be selected. Furthermore, counter-lamination laminations 7, 2 can also be provided in a suitable manner for the low-voltage conductor arrangements 6 in order to adjust the stray inductance and / or reduce eddy current losses and / or vary the length of the respective parallel-connected main laminations 7, 1.

[0020] Figure 4 shows a variant according to the invention in which the laminations 7 are each formed from a plurality of lamination strips 10 arranged adjacent to one another in a direction transverse to the stacking direction. Thanks to the slots then present between adjacent lamination strips 10 of a lamination 7, eddy current losses can be reduced. Counter-lamination strips (not shown in detail) can also be arranged between the lamination strips 10 in order to achieve the effects described above.

[0021] Although the invention has been illustrated and described in detail by the preferred embodiment, the invention is not limited by the disclosed examples, and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention. Thus, the transformer core can be designed as a toroidal core and also have two core limbs, around each of which one or more conductor arrangements is / are arranged, thereby dividing the current flow. Transformer cores with more than three core limbs are also conceivable.

[0022] Regardless of the grammatical gender of a particular term, persons with male, female or other gender identity are included.

Claims

Patent claims 1. Transformer (1), in particular a medium-frequency transformer, comprising a transformer core (2) with a plurality of core limbs (4) which are connected to one another via yokes (3), and at least two conductor arrangements (5, 6) which are arranged around at least one of the core limbs (4), characterized in that each conductor arrangement (5, 6) is designed as a lamination stack with a plurality of laminations (7) arranged one above the other in a stacking direction.

2. Transformer (1) according to claim 1, characterized in that the sheet metal laminations (7) have an electrically insulating coating.

3. Transformer (1) according to claim 1 or 2, characterized in that the sheet metal laminations (7) are each U-shaped.

4. Transformer (1) according to one of the preceding claims, characterized in that the laminations (7) are each formed from a plurality of lamination strips (10) which are arranged adjacent to one another in a direction transverse to the stacking direction and are preferably U-shaped.

5. Transformer (1) according to one of the preceding claims, characterized in that the lamination stack of at least one conductor arrangement (5, 6) has main laminations (7.1) and counter laminations (7.2) which are electrically connected to one another, wherein the counter laminations (7.2) have a shorter length than the main laminations (7.1).

6. Transformer (1) according to one of the preceding claims, characterized in that in at least one conductor arrangement (6) sheet metal laminations are electrically connected in parallel in the stacking direction.

7. Transformer (1) according to one of the preceding claims, characterized in that the transformer core (2) has at least three adjacently arranged core limbs (4), that at least two high-voltage windings (5) and at least two low-voltage windings (6) are arranged on the central core limb (4), that the at least two high-voltage windings (5) are positioned between the low-voltage windings (6), and that the laminations (7.1) of the high-voltage winding (5) are arranged in series in the stacking direction and laminations (7.1) of the low-voltage windings (6), in particular all laminations (7.1) of the low-voltage windings (6) are connected in parallel in the stacking direction.

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