MAGNETIC CORE, AND CHOKE OR TRANSFORMER HAVING SUCH A MAGNETIC CORE

Abstract

The invention relates to a magnetic core (10) for a three-phase choke or a three-phase transformer, comprising three winding legs (11, 12, 13) for holding electrical windings (21, 22, 23), wherein the winding legs (11, 12, 13) are arranged substantially parallel to each other in the shape of a triangle, wherein the winding legs (11, 12, 13) are connected by means of an annular or convex polygonal yoke (14), which lies on the winding legs (11, 12, 13). The invention also relates to a choke or transformer having such a magnetic core (10).

Claims

1. Magnetic core (10) for a three-phase choke or a three-phase transformer having three winding legs (11, 12, 13) for holding electrical windings (21, 22, 23), wherein the winding legs (11, 12, 13) are arranged substantially parallel to each other in the shape of a triangle, characterized in that the winding legs (11, 12, 13) are connected by an annular or convex polygonal yoke (14), which rests on the winding legs (11, 12, 13).

2. Magnetic core(10) according to claim 1, characterized in that the yoke (14) rests on the longitudinal ends of the winding legs (11, 12, 13).

3. Magnetic core (10) according to claim 1 or 2, characterized in that the yoke (14) has three cross-connecting legs (15, 16, 17), each cross-connecting leg (15, 16, 17) connecting two directly adjacent winding legs (11, 12, 13).

4. Magnetic core (10) according to claim 3, characterized in that a first cross-connecting leg (15) connects a first and second winding leg (11, 12) to each other, a second cross-connecting legs (16) connects a second and third winding leg (12, 13) to each other, and a third cross-connecting leg (17) connects the third and first winding legs (13, 11) to each other.

5. Magnetic core (10) according to any one of the preceding claims, characterized in that the yoke (14), in particular the cross-connecting legs (15, 16, 17), form a closed shaped element having a preferably centrally arranged through opening (19).

6. Magnetic core (10) according to any one of the preceding claims, characterized in that the yoke (14) is formed from a single part or multiple parts.

7. Magnetic core (10) according to any one of the preceding claims, characterized in that the yoke (14) and/or the winding legs (11, 12, 13) are formed by a compressed powder composite material.

8. Magnetic core (10) according to claim 7, characterized in that the powder composite material comprises iron, nickel, silicon, aluminium and/or molybdenum.

9. Magnetic core (10) according to any one of the preceding claims, characterized in that the yoke (14) is in the shape of a triangle or hexagon.

10. Magnetic core (10) according to any one of the preceding claims, characterized in that the yoke (14) has an equilateral and/or equal-angled design, in particular, having the form of a regular polygon.

11. Magnetic core (10) according to any one of the preceding claims, characterized in that the winding legs (11, 12, 13) have a circular or rectangular cross-section.

12. Magnetic core (10) according to any one of the preceding claims, characterized in that the yoke (14) is adhesively bonded to the winding legs (11, 12, 13), in particular to the longitudinal ends of the winding legs (11, 12, 13).

13. Magnetic core (10) according to any one of the preceding claims, characterized in that a discharge leg, which is connected to the yoke (14), is arranged centrally between the three winding legs (11, 12, 13).

14. Three-phase choke or three-phase transformer having a magnetic core (10) according to any one of the preceding claims and having at least one electrical winding (21, 22, 23), which is wound around one of the winding legs (11, 12, 13).

15. Choke or transformer according to claim 14, characterized in that the winding (21, 22, 23) is formed by a flat wire, in particular a flat enamelled copper wire.

Description

[0036] The invention is described in greater detail in the following by reference to the attached schematic drawings. They show:

[0037] FIG. 1: a side view of a choke according to the invention or a transformer according to a preferred exemplary embodiment;

[0038] FIG. 2: a plan view of the choke or the transformer in accordance with FIG. 1; and

[0039] FIG. 3: a plan view of an alternative choke or an alternative transformer according to a preferred exemplary embodiment.

[0040] FIG. 1 shows a three-phase choke or a three-phase alternating current choke in a side view. The choke comprises a magnetic core 10 with three winding legs 11, 12, 13. The three winding legs 11, 12, 13 are arranged substantially parallel to each other, or extend parallel to a longitudinal axis of the choke. At their longitudinal ends 18 the winding legs 11, 12, 13, are each connected to a yoke 14. The yoke 14 couples the three winding legs 11, 12, 13 to each other magnetically. The yoke 14 can also be adhesively bonded to the winding legs 11, 12, 13.

[0041] In general, the winding legs 11, 12, 13 and the yoke 14 can be produced from a powder composite material. The magnetic core overall is in that case implemented as a powder core. The use of a powder core material has the advantage that during the production of the magnetic core 10 microscopic air gaps are formed within the magnetic core 10, which are advantageous for the magnetic permeability. It is generally advantageous for a uniform magnetic flux or a uniform magnetic resistance if the yoke 14 and the winding legs 11, 12, 13 are made from the same material.

[0042] In one embodiment, not shown here, it can be provided that a fourth winding leg is arranged centrally between the three winding legs 11, 12, 13 as a discharge leg. The fourth winding legs can have a ferrite core and be suitable for conducting a magnetic field that can be produced due to asymmetries in the three-phase system.

[0043] In particular, the fourth discharge leg can be made smaller than the three winding legs 11, 12, 13 and conduct asymmetrical harmonic components. In the fourth discharge leg, high-frequency alternating magnetic fields are produced, which leads to an improvement in the symmetry of a three-phase choke. The same applies to a three-phase transformer, which differs from the three-phase choke only in the fact that additional windings are applied to the winding legs 11, 12, 13.

[0044] As is additionally shown in FIG. 1, the yoke 14 and the winding legs 11, 12, 13 have substantially the same thickness. This also achieves an improvement of the magnetic flux while simultaneously reducing the material used.

[0045] The three winding legs 11, 12, 13 comprise a first winding leg 11, a second winding leg 12 and a third winding leg 13. The first winding leg 11 carries a first winding 21. The second winding leg 12 carries a second winding 22. The third winding leg 13 carries a third winding 23. The windings 21, 22, 23 can have the same design. The windings 21, 22, 23 are preferably formed by a copper wire, in particular an enamelled copper wire.

[0046] It is particularly advantageous to use a flat wire or a flattened enamelled copper wire. This means that for an increased conductor cross-section capable of carrying correspondingly high currents, the total assembled size of the choke can be reduced. In particular, the height of the windings 21, 22, 23 can be reduced in this way, while high currents can still be carried.

[0047] The individual windings 21, 22, 23 each have two winding connections 20 that are used for the electrical connection of the windings 21, 22, 23. It is preferred if each of the windings 21, 22, 23 is assigned to different phases of a three-phase system. Thus the first winding 21 can be assigned to a first electrical phase L1, the second winding 22 to a second electrical phase L2, and the third winding 23 to a third electrical phase L3.

[0048] FIGS. 2 and 3 show two different exemplary embodiments of a choke, which differ from each other in the geometrical form of the yoke 14. The side view according to FIG. 1 applies to both exemplary embodiments in accordance with FIGS. 2 and 3.

[0049] In FIG. 2, it is apparent that the yoke 14 is annular. The magnetic core 10 therefore comprises an annular yoke 14. The annular yoke 14 has a through-opening 19, which is circular in design. The width of the annular yoke 14 substantially corresponds to the diameter of the winding legs 11, 12, 13. The yoke 14 thus rests with its full surface on the winding legs 11, 12, 13, in particular on their longitudinal ends 18.

[0050] In concrete terms, the yoke 14 comprises three cross-connecting legs 15, 16, 17, each of which is arcuate in shape. A first cross-connecting leg 15 connects the first and second winding legs 11, 12 to each other. A second cross-connecting leg 16 connects the second winding leg 12 to the third winding leg 13. The third winding leg 13 and the first winding leg 11 are magnetically coupled by a third cross-connecting leg 17 of the yoke 14.

[0051] As is also clearly apparent from FIG. 2, the yoke 14 and the end faces of the windings 21, 22, 23 have comparatively large overlap regions.

[0052] The yoke 14 thus covers a relatively large proportion of the windings 21, 22, 23 and offers protection against damage in the longitudinal axial direction. In addition, the yoke 14 extends as far as the outer edge of the choke as a whole and thus also acts as a stop in a radial direction relative to a central longitudinal axis of the choke.

[0053] FIG. 3 shows an alternative design of the yoke 14, wherein the yoke forms a polygonal shape. Specifically, the choke shown in FIG. 3 is equipped with a triangular yoke 14, which has a triangular through-opening 19. The triangular yoke 14 also has three cross-connecting legs 15, 16, 17, which each connect the first, second and third winding legs 11, 12, 13 to each other. The cross-connecting legs 15, 16, 17 extend in a straight line between two adjacent winding legs 11, 12, 13. An intersection or junction of the cross-connecting legs 15, 16, 17 takes place at each of the longitudinal ends 18 of the winding legs 11, 12, 13.

[0054] It is also apparent in FIG. 3 that the triangular design of the yoke 14 gives rise to a relatively large region of overlap between the yoke surface and the end face of the windings 21, 22, 23. In this respect, the yoke 14 according to FIG. 3 also offers increased protection against damage to the windings 21, 22, 23. Also, the cross-connecting legs 15, 16, 17 preferably have a width which is equal to the diameter of the winding legs 11, 12, 13. This facilitates a good magnetic flux and also reduces the material costs for the magnetic core 10.

[0055] In FIGS. 2 and 3 the winding legs 11, 12, 13 are each designed as rounded core legs. However, it is also possible to provide the winding legs 11, 12, 13 with a rectangular cross-sectional geometry. The width of the yoke 14, and in particular of the cross-connecting legs 15, 16, 17, must then be adapted accordingly.

[0056] As is evident in the two exemplary embodiments in accordance with FIGS. 2 and 3, the annular or convex polygonal yoke 14 offers an improved footprint for the choke. In particular, the selected geometry facilitates the stackability of a plurality of magnetic cores 10 of chokes or transformers, which are fitted with the magnetic core 10. In addition, it is apparent that the triangular-shaped arrangement of the winding legs 11, 12, 13 leads to a compact design of the choke overall. At the same time, by using appropriate spacing distances between the individual winding legs 11, 12, 13 an improved cooling of a choke or transformer can be achieved. This is also promoted by the through-opening 19 in the yoke 14. A further contribution to the cooling of the choke or the transformer is provided by the nature of the windings 21, 22, 23. The windings 21, 22, 23 are preferably formed by a flat wire, which also improves the cooling with an appropriate winding interval. The choke or transformer therefore has a better performance overall.

[0057] The triangular-shaped yoke 14 preferably forms an isosceles triangle, particularly preferably an equilateral triangle. This enables a particularly compact design. In addition, the stackability of the magnetic core 10 is also improved. In the equilateral design of the triangular yoke 14, the cross-connecting legs 15, 16, 17 are arranged at an angle of 60 to one another.

LIST OF REFERENCE NUMERALS

[0058] 10 magnetic core [0059] 11 first winding leg [0060] 12 second winding leg [0061] 13 third winding leg [0062] 14 yoke [0063] 15 first cross-connecting leg [0064] 16 second cross-connecting leg [0065] 17 third cross-connecting leg [0066] 18 longitudinal end [0067] 19 through-opening [0068] 20 winding connection [0069] 21 first winding [0070] 22 second winding [0071] 23 third winding