Integral Inductor Arrangement

Abstract

The disclosure relates to an integral inductor arrangement with at least three magnetic loops arranged side by side to each other in a row and at least one winding associated with each of the magnetic loops. The magnetic loops are formed by individual core elements, each of which being part of one of the magnetic loops, and shared core elements, each of which being part of two adjacent of the magnetic loops. The shared core elements are separated from the individual core elements by magnetic gaps and each of the at least one winding is arranged around one of the individual core elements. The disclosure further relates to a use of such integral inductor arrangement within a 3-phase AC-filter for a power inverter for feeding electrical power into a power grid.

Claims

1. An integral inductor arrangement with at least three magnetic loops arranged side by side to each other in a row and at least one winding associated with each of the magnetic loops, the magnetic loops being formed by individual core elements, each of which being part of one of the magnetic loops, and shared core elements, each of which being part of two adjacent of the magnetic loops, wherein the shared core elements are separated from the individual core elements by magnetic gaps and each of the at least one winding is arranged around one of the individual core elements and not arranged around the magnetic gaps, wherein each of the at least one winding defines a respective one of the magnetic loops, and further wherein the magnetic gaps comprise dielectric distance pieces, air gaps or magnetic materials having a lower permeability than the individual or shared core elements.

2. The integral inductor arrangement according to claim 1, wherein the shared core elements are arranged perpendicular to the individual core elements.

3. The integral inductor arrangement according to claim 1, wherein the individual core elements and the shared core elements have the same cross-sectional area.

4. The integral inductor arrangement according to claim 1, wherein the windings associated with two adjacent of the magnetic loops have a different sense of winding.

5. The integral inductor arrangement according to claim 1, wherein the shared core elements are cuboidal blocks.

6. The integral inductor arrangement according to claim 1, wherein two of the magnetic loops are outer magnetic loops that are positioned around an inner magnetic loop, wherein the individual core elements of the outer magnetic loops are c-shaped.

7. The integral inductor arrangement according to claim 6, wherein the individual core element of each of the outer magnetic loops comprises three cuboidal blocks.

8. The integral inductor arrangement according to claim 6, wherein the individual core element of the inner magnetic loop comprises two cuboidal blocks.

9. The integral inductor arrangement according to claim 5, wherein all cuboidal blocks are of equal size.

10. The integral inductor arrangement according to claim 1, wherein individual core elements that carry a winding have an elliptical cross section.

11. The integral inductor arrangement according to claim 1, wherein the individual and/or shared core elements are made of stamped silicon steel sheets stacked to form a laminated structure.

12. The integral inductor arrangement according to claim 1, wherein the individual and/or shared core elements are made of ferrite.

13. The integral inductor arrangement according to claim 1, wherein the individual and/or shared core elements are made of laminated magnetic amorphous metal.

14. The integral inductor arrangement according to claim 1, wherein the individual and/or shared core elements are made of sintered powder of magnetic material.

15. The integral inductor arrangement according to claim 1, wherein individual core elements that carry a winding are made of sintered powder of magnetic material and all other individual core elements and the shared core elements are made of high magnetic permeability material.

16. The integral inductor arrangement according to claim 1, wherein the windings are wound on bobbins.

17. The integral inductor arrangement according to claim 16, wherein the bobbins have means for fixing the shared core elements.

18. The integral inductor arrangement according to claim 1, wherein the arrangement of core elements is secured by a compressing force.

19. The integral inductor arrangement according to claim 18, wherein the compressing force originates from bolts acting on two clamps, positioned on each head end of the arrangement.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The disclosure will be explained in more detail in the following text using exemplary embodiments and with the aid of three figures, in which:

[0018] FIGS. 1A and 1B show an example embodiment of an integral inductor arrangement;

[0019] FIG. 2 shows an example setup of an AC-filter for which the integral inductor arrangement according to the present disclosure can be used; and

[0020] FIG. 3 shows a diagram of the time-dependence of the magnetic flux in a shared core element of an integral inductor arrangement.

DETAILED DESCRIPTION

[0021] FIG. 1 a shows a top view of an integral inductor arrangement according to the application. FIG. 1b depicts a sectional view of the integral inductor arrangement along the line A-A indicated in FIG. 1a.

[0022] In the given example, the integral inductor arrangement comprises six windings 1 forming three pairs, where each pair is associated with one of three magnetic loops a, b, c. The loops are defined by core elements 2, 3 that show a high magnetic permeability. The core elements 2, 3 are, for example, made of stamped silicon steel sheets stacked to form a laminated structure, of ferrite, of laminated magnetic amorphous metal, or of sintered magnetic powder.

[0023] The magnetic loops a, b, c are arranged along a line, side by side to each other. Thus, one inner magnetic loop b is flanked by two outer magnetic loops a, c, one on each side of the inner magnetic loop b.

[0024] The core elements 2, 3 that form and define the magnetic loops a, b, c can be distinguished into individual core elements 2 which belong to one magnetic loop a, b, c only and shared core elements 3 which are shared by two adjacent magnetic loops a, b or b, c, respectively. The windings 1 are positioned on individual core elements 2 only and not on the shared core elements 3. The shared core elements 3 are separated from the individual core elements 2 by magnetic gaps 4, which are e.g. formed by a dielectric plate. The magnetic gaps 4 are small sections of a low magnetic permeability. They decouple the magnetic loops a, b, c from each other.

[0025] Since the windings 1 are positioned on the individual core elements 2, the windings 1 are accordingly not wound around the magnetic gaps 4. As a result, a fringing flux due to the magnetic windings 1 does not influence the windings 1, thereby reducing magnetic losses and enhancing the efficiency of the inductor arrangement. Advantageously, the windings 1 associated with two adjacent magnetic loops a, b and b, c have different senses of winding, as also indicated by the stars in FIG. 2 and described below in connection with FIG. 2.

[0026] In one embodiment the two shared core elements 3 are cuboidal shape. The individual core elements 2 of the outer magnetic loops a, c are c-shaped. Each could be formed by a single c-shaped piece. However, as shown in the example, each may also be formed by three cuboidal blocks, arranged in c-shape. The three blocks may be optionally separated from each other by further magnetic gaps 5. The individual core elements 2 of the inner magnetic loop b may comprise or consist of two cuboidal blocks. Thus, in the advantageous embodiment shown in FIG. 1b, the core of the integral inductor arrangement is composed of ten cuboidal blocks of which two blocks (shared core elements 3) and the blocks on each side are orthogonally placed to the remaining six blocks that are organized in two parallel lines by three blocks each. The ten cuboidal blocks may be of equal size and material, thereby decreasing costs for production and storage.

[0027] In one embodiment the windings 1 are arranged on bobbins 6 that are equipped with appropriate fixing means, e.g. a skirting, which provide support for the shared core elements 3 when the bobbins 6 are positioned on the individual core elements 2. The whole arrangement of the core elements 2, 3 may be fixed by compressing the arrangement along its longitudinal axis using two long screws 7 or bolts and profiled clamps 8, for example, made from metal.

[0028] The advantageous circumstances for using the integral inductor arrangement according to the application in a three-phase AC-filter 10 as shown in FIG. 2 are explained in connection with FIG. 3. FIG. 3 shows the time dependence of a first magnetic flux 21 that exists in one of the outer magnetic loops a,c of the arrangement shown in FIG. 1 and a second magnetic flux 22 that exists in the inner magnetic loop b. Both magnetic fluxes 21, 22 are shown in arbitrary units, scaled to an amplitude of one. The time dependence is shown as a phase angle in degrees, i.e. the diagram shows one period of the grid frequency. The magnetic fluxes 21, 22 are proportional to the currents in the respective windings. Due to the nature of the three-phase current, the magnetic fluxes 21, 22 are shifted by 120° with respect to each other.

[0029] FIG. 2 shows a three-phase AC-filter 10 that is arranged, for example, between a power inverter and a power grid in a schematic wiring diagram. The AC-filter 10 has three inputs 11a, 11b, 11c that are connected to the three output-lines of the inverter and a further input 11 n connected to a neutral line. Three outputs 12a, 12b, 12c then lead to the respective lines of a power grid. The AC-filter 10 comprises three first inductors 13a, 13b, 13c, three second inductors 14a, 14b, 14c and three capacitors 15a, 15b, 15c. According to the disclosure, the first inductors 13a, 13b, 13c and/or the three second inductors 14a, 14b, 14c may be provided by an integral inductor arrangement, e.g. the one shown in FIG. 1. By way of example, the box 13 in FIG. 2 indicated that the three first inductors 13a, 13b, 13c are integral in this case. A different sense of winding of adjacent magnetic loops a, b, c of the integral inductor arrangement is indicated by the stars next to the winding-symbol in the figure.

[0030] A third magnetic flux 23 which is the sum of the two magnetic fluxes 21 and 22 is shown in FIG. 3. This third magnetic flux 23 represents the time dependence of the flux in one of the shared core elements 3. It is apparent that this flux never exceeds the maximum value of the flux density of any of the single components, i.e. the magnetic fluxes 21, 22. Due to this fact it is possible to reduce the cross-sectional area of the shared core elements 3 to the cross-sectional area of the individual core elements and thus to a value smaller than that of two blocks as in a simple combination of discrete setups, without the risk to exceeding the maximum flux density for the magnetic material used.