DC inductor

• US 7,889,040 B2
• Filed: 06/06/2008
• Issued: 02/15/2011
• Est. Priority Date: 06/08/2007
• Status: Active Grant

• Current Assignee: ABB Schweiz AG (ABB Limited)
• Original Assignee: Abb Oy (ABB Limited)
• Inventors: Hautakorpi, Esa, Pieteris, Paulius, Viitanen, Tero
• Primary Examiner(s): Mai; Anh T
• Application Number:
  US12/155,632
• Publication Number:
  US 20080303620A1
• Time in Patent Office: 984 Days
• Field of Search: 336/212, 336/214, 336/219, 336/178, 336/110
• US Class Current: 336/110
• CPC Class Codes: H01F 2003/103 Magnetic circuits with permanent magnets
• CPC Class Codes: H01F 27/385 for reducing harmonics
• CPC Class Codes: H01F 3/14 Constrictions; Gaps, e.g. air-gaps in magnetic shunt paths H01F3/12
• CPC Class Codes: H01F 37/00 Fixed inductances not covered by group H01F17/00

Abstract

A DC inductor comprising a core structure (11) comprising one or more magnetic gaps (12, 13), a coil (14) wound on the core structure (11), at least one permanent magnet (15) positioned in the core structure, the magnetization of the permanent magnet (15) opposing the magnetization producible by the coil (14). The DC inductor further comprises at least one magnetic slab (16) inserted to the core structure which forms the one or more magnetic gaps (12, 13), at least one supporting member (17) made of magnetic material extending from the core structure inside the core structure and supporting the at least one permanent magnet (15), and that the at least one supporting member (17) is arranged to form a magnetic path for the at least one permanent magnet.

Claims

1. A DC inductor comprising

a core structure comprising one or more magnetic gaps,

a coil inserted on the core structure,

at least one permanent magnet positioned in the core structure, the magnetization of the permanent magnet opposing the magnetization producible by the coil,

wherein the DC inductor further comprises at least one magnetic slab inserted to the core structure to form one or more magnetic gaps,

at least one supporting member made of magnetic material extending from the core structure inside the core structure and supporting the at least one permanent magnet,

and that the at least one supporting member is arranged to form a magnetic path for the at least one permanent magnet.

2. A DC inductor according to claim 1, wherein the at least one supporting member is arranged to extend parallel to the core structure and the at least one permanent magnet is arranged between the at least one supporting member and the core structure such that the at least one supporting member forms together with the core structure a low reluctance magnetic path for the at least one permanent magnet.

3. A DC inductor according to claim 2, wherein the at least one magnetic slab, which is used to define the magnetic gap, is arranged on the supporting member and arranged to form part of the magnetic path for the magnetization producible by the coil.

4. A DC inductor according to claim 1, wherein the core structure comprises an upper leg and that the supporting member extends parallel to the upper leg inside the core structure, the distance between the upper leg and the supporting member corresponding to the dimension of the at least one permanent magnet.

5. A DC inductor according to claim 1, wherein the core structure comprises a first U-shaped core and a second U-shaped core, whereby the second U-shaped core is arranged inside the first U-shaped core such that the legs of the second U-shaped core are arranged to form the supporting members that extend parallel to the core structure inside the core structure.

6. A DC inductor according to claim 5, wherein the DC inductor comprises at least two permanent magnets, which are arranged between outer surfaces of the legs of the second U-shaped core and inner surfaces of legs of the first U-shaped core.

7. A DC inductor according to claim 5, wherein the magnetic path for the magnetization producible by the coil is formed of the first U-shaped core, a base of the second U-shaped core, which base combines the legs of the second U-shaped core, and at least two magnetic slabs, which are arranged between the inner end surfaces of the legs of the first U-shaped core and the outer side surface of the base of the second U-shaped core.

8. A DC inductor according to claim 1, wherein the DC inductor comprises two supporting members, both of which extend from the core structure both inside and outside the core structure, the supporting members being arranged to hold the at least two permanent magnets between them and that the magnetic slab is inserted in the core structure between the supporting members.

9. A DC inductor according to claim 8, wherein the supporting members provide a low reluctance magnetic path for the magnetization produced by the permanent magnets.

10. A DC inductor according to claim 1, wherein the core structure comprises three parallel legs and the supporting member is arranged inside the core structure to hold at least two permanent magnets between the supporting member and the core structure.

11. A DC inductor according to claim 10, wherein the supporting member and the magnetic slab are arranged to form at least one magnetic gap in the core structure to the magnetic path for the magnetization producible by the coil.

12. A DC inductor according to claim 10, wherein the supporting member is arranged on the center leg of the core structure and the permanent magnets are arranged on both ends of the supporting member, while the air gap is situated between the permanent magnets in the center leg.

13. A DC inductor according to claim 10, wherein the supporting member provides a low reluctance magnetic path for the magnetization of permanent magnets between the outer core structure and center leg.

14. A DC inductor according to claim 10, wherein the coil is wound on one or more legs of the core structure.

15. A DC inductor according to claim 1, wherein the core structure comprises three parallel legs and two supporting members are arranged inside the core structure to hold at least two permanent magnets between the supporting members.

16. A DC inductor according to claim 15, wherein the supporting members are arranged on the center leg and magnetic slab is arranged between the supporting members producing the magnetic gap to the center leg of the core structure.

17. A DC inductor according to claim 15, wherein supporting members provide a gapless magnetic path for the magnetization of the permanent magnets.

18. A DC inductor according to claim 15, wherein the DC inductor comprises coils wound on one or more legs of the core structure.

19. A DC inductor according to claim 15, wherein the coil is wound on the center leg of the core structure and arranged to surround the supporting members, permanent magnets (65, 66) and the magnetic slab.

20. A DC inductor according to claim 1, wherein some or each of the one or more magnetic gaps are uniform gaps.

21. A DC inductor according to claim 1, wherein some or each of the one or more magnetic gaps are non-uniform gaps.