Monolithic inductor

• US 20080157912A1
• Filed: 07/03/2007
• Published: 07/03/2008
• Est. Priority Date: 12/28/2006
• Status: Active Grant

• Current Assignee: Industrial Technology Research Institute
• Original Assignee: Industrial Technology Research Institute
• Inventors: Wang, Yen-Ping, Huang, Yu-Ting, Tung, Mean-Jue, Ko, Wen-Song
• Granted Patent: US 8,054,149 B2
• Time in Patent Office: Days
• US Class Current: 336/200
• CPC Class Codes: H01F 17/04 with magnetic core
• CPC Class Codes: H01F 2003/103 Magnetic circuits with permanent magnets
• CPC Class Codes: H01F 2017/046 helical coil made of flat wire, e.g. with smaller extension of wire cross section in the direction of the longitudinal axis
• CPC Class Codes: H01F 27/255 made from particles H01F27/26 takes precedence
• CPC Class Codes: H01F 27/34 Special means for preventing or reducing unwanted electric or magnetic effects, e.g. no-load losses, reactive currents, harmonics, oscillations, leakage fields
• CPC Class Codes: H01F 41/0246 Manufacturing of magnetic circuits by moulding or by pressing powder magnetic cores made by moulding or by pressing powder H01F27/255; soft magnetic particles H01F1/20, H01F1/36

Abstract

This invention discloses a monolithic inductor including a body made by compressing a magnetic powder, a coil positioned in the body, and a permanent magnet positioned in the body and in a magnetic circuit formed by applying current to the coil. The monolithic inductor of this invention includes the magnetic body containing the permanent magnet and the coil. The permanent magnet in the magnetic circuit (path of magnetic flux lines) formed by applying current to the coil generates a reverse-bias magnetic field, thereby increasing the operating range of the magnetic body, the saturation current of the magnetic body, and the rated current of the inductor.

Claims

1. A monolithic inductor, comprising:

a body made by compressing a magnetic powder;

a coil positioned in the body; and

a permanent magnet positioned in the body and in a magnetic circuit formed by applying current to the coil.

2. The monolithic inductor according to claim 1, wherein the magnetic field of the permanent magnet is parallel to a magnetic field formed by applying current to the coil.

3. The monolithic inductor according to claim 1, wherein the magnetic field of the permanent magnet is anti-parallel to a magnetic field formed by applying current to the coil.

4. The monolithic inductor according to claims 1, wherein the permanent magnet is positioned inside a hollow region circumferentially defined by the coil, has an area equal to an area of the hollow region circumferentially defined by the coil, and has a thickness ranging from 0.1 mm to a thickness of the body.

5. The monolithic inductor according to claims 1, wherein the permanent magnet is positioned outside a hollow region circumferentially defined by the coil and has an area denoted by A and a thickness by B, the area A being not less than an area of the hollow region circumferentially defined by the coil and not greater than a cross-sectional area of the body, the thickness B being not less than 0.1 mm and not greater than a distance between a surface of the body and one side of the coil opposite the surface of the body.

6. The monolithic inductor according to claim 5, wherein a thickness of the body is denoted by C and a height of the coil by D, and the thickness of the permanent magnet ranges from 0.1 mm to ((C−

D)/2).

7. The monolithic inductor according to claim 1, wherein the body is made of a magnetically permeable metal.

8. The monolithic inductor according to claim 7, wherein the metal is one selected from the group consisting of iron (Fe), cobalt (Co), nickel (Ni), and a compound thereof.

9. The monolithic inductor according to claim 1, wherein the body is made of a magnetic oxide of one selected from the group consisting of iron (Fe), cobalt (Co), and nickel (Ni).

10. The monolithic inductor according to claim 9, wherein the magnetic oxide is one selected from the group consisting of manganese-zinc (MnZn) ferrite, nickel-zinc (NiZn) ferrite, copper-zinc (CuZn) ferrite, and lithium-zinc (LiZn) ferrite.

11. The monolithic inductor according to claim 1, wherein the permanent magnet is made of one selected from the group consisting of neodymium-iron-boron (NdFeB), samarium-cobalt (SmCo), aluminum-nickel-cobalt (AlNiCo), barium-ferrite (Ba-ferrite), and strontium-ferrite (Sr-ferrite).

12. The monolithic inductor according to claim 1, wherein the permanent magnet is primarily made of one selected from the group consisting of neodymium-iron-boron (NdFeB), samarium-cobalt (SmCo), aluminum-nickel-cobalt (AlNiCo), barium-ferrite (Ba-ferrite), and strontium-ferrite (Sr-ferrite) and secondarily made of a magnetically permeable metal selected from the group consisting of metal, metallic compound, and magnetic metal oxide.

13. The monolithic inductor according to claim 12, wherein the material having magnetic permeability is one selected from the group consisting of iron (Fe), cobalt (Co), nickel (Ni), a compound thereof, and a magnetic oxide thereof.

14. The monolithic inductor according to claim 13, wherein the magnetic metal oxide is one selected from the group consisting of manganese-zinc (MnZn) ferrite, nickel-zinc (NiZn) ferrite, copper-zinc (CuZn) ferrite, and lithium-zinc (LiZn) ferrite.

15. The monolithic inductor according to claim 1, wherein the coil is made of one selected from the group consisting of copper (Cu), aluminum (Al), silver (Ag), and a combination thereof.

16. A monolithic inductor, comprising:

a body made by compressing a magnetic powder;

a coil positioned in the body; and

a permanent magnet positioned on a surface of the body and in a magnetic circuit formed by applying current to the coil.

17. The monolithic inductor according to claim 16, wherein the magnetic field of the permanent magnet is parallel to a magnetic field formed by applying current to the coil.

18. The monolithic inductor according to claim 16, wherein the magnetic field of the permanent magnet is anti-parallel to a magnetic field formed by applying current to the coil.

19. The monolithic inductor according to claims 16, wherein the permanent magnet has an area denoted by A and a thickness not less than 0.1 mm, the area A being not less than an area of the hollow region circumferentially defined by the coil and not greater than a cross-sectional area of the body.

20. The monolithic inductor according to claim 19, wherein a thickness of the body is denoted by C and a height of the coil by D, and the thickness of the permanent magnet ranges from 0.1 mm to ((C-D)/2).

21. The monolithic inductor according to claim 16, wherein the body is made of a magnetically permeable metal.

22. The monolithic inductor according to claim 21, wherein the metal is one selected from the group consisting of iron (Fe), cobalt (Co), nickel (Ni), and a compound thereof.

23. The monolithic inductor according to claim 16, wherein the body is made of a magnetic oxide of one selected from the group consisting of iron (Fe), cobalt (Co), and nickel (Ni).

24. The monolithic inductor according to claim 23, wherein the magnetic metal oxide is one selected from the group consisting of manganese-zinc (MnZn) ferrite, nickel-zinc (NiZn) ferrite, copper-zinc (CuZn) ferrite, and lithium-zinc (LiZn) ferrite.

25. The monolithic inductor according to claim 16, wherein the permanent magnet is made of one selected from the group consisting of neodymium-iron-boron (NdFeB), samarium-cobalt (SmCo), aluminum-nickel-cobalt (AlNiCo), barium-ferrite (Ba-ferrite), and strontium-ferrite (Sr-ferrite).

26. The monolithic inductor according to claim 16, wherein the permanent magnet is primarily made of one selected from the group consisting of neodymium-iron-boron (NdFeB), samarium-cobalt (SmCo), aluminum-nickel-cobalt (AlNiCo), barium-ferrite (Ba-ferrite), and strontium-ferrite (Sr-ferrite) and secondarily made of a magnetically permeable metal selected from the group consisting of metal, metallic compound, and metal oxide.

27. The monolithic inductor according to claim 26, wherein the material having magnetic permeability is one selected from the group consisting of iron (Fe), cobalt (Co), nickel (Ni), a compound thereof, and a magnetic oxide thereof.

28. The monolithic inductor according to claim 27, wherein the magnetic metal oxide is one selected from the group consisting of manganese-zinc (MnZn) ferrite, nickel-zinc (NiZn) ferrite, copper-zinc (CuZn) ferrite, and lithium-zinc (LiZn) ferrite.

29. The monolithic inductor according to claim 16, wherein the coil is made of one selected from the group consisting of copper (Cu), aluminum (Al), silver (Ag), and a combination thereof.