# US 11,309,109 B2 · Inductive core exhibiting low magnetic losses

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- Number: US 11,309,109 B2
- Document ID: US11309109B2
- Status: Granted
- Kind: B2
- Application number: 16/062,693
- Filed: 2016-12-16
- Published: 2018-12-27
- Granted: 2022-04-19
- Earliest claimed: 2015-12-17
- Assignees: Commissariat A L'energie Atomique Et Aux Energies Alternatives
- Applicants: Commissariat A L'energie Atomique Et Aux Energies Alternatives
- Inventors: Gerard Delette
- Web page: https://patentgrep.com/patent/US11309109B2

## CPC

- H01F 3/10: Composite arrangements of magnetic circuits
- H01F 3/14: Constrictions; Gaps, e.g. air-gaps (in magnetic shunt paths H01F3/12)
- H01F 27/22: Cooling by heat conduction through solid or powdered fillings
- 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)}
- H01F 2003/103: {Magnetic circuits with permanent magnets}
- H01F 2003/106: {Magnetic circuits using combinations of different magnetic materials}
- H01F 2038/026: {non-linear inductive arrangements for converters, e.g. with additional windings}
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES

## Abstract

An inductive core including a body including a ferromagnetic material and a magnet, the magnet forming a first path for circulating of magnetic flux lines produced by the magnet, and the ferromagnetic material at least partially forming a second path for circulating the magnetic flux lines, wherein the ferromagnetic material extends continuously between the poles of the magnet along the poles of the magnet and makes contact with at least a part of an exterior lateral wall of the magnet extending between its poles.

## Claims

### Claim 1

An inductor core for magnetic inductor, comprising:
a body comprising a ferromagnetic material and one or more magnets, in which the one or more magnets at least partially form a first path for circulating magnetic flux lines produced by the one or more magnets such that the first path comprises at a first end a designated end south pole, and at a second end a designated end north pole, and
wherein the ferromagnetic material at least partially forms a second path for circulating the magnetic flux lines,
wherein the ferromagnetic material extends continuously from the south pole to the north pole along the one or more magnets, and comprising, facing the end south pole, a non-magnetic zone and, facing the end north pole, a non-magnetic zone forcing the magnetic flux lines coming out of the end north pole to take the second path and to loop back on the end south pole, the non-magnetic zones being designated end non-magnetic zones, such that a transversal section of the inductor core, perpendicular to the flux lines, comprises both the first path for circulating and the second path for circulating,
wherein each of the one or more magnets is disposed in a cavity of the body such that a lateral face of each magnet is at least partly surrounded by ferromagnetic material of the body.

### Claim 2 (depends on 1)

An inductor core according to claim 1, wherein each of the one or more magnets comprises an exterior lateral face between the south pole and the north pole, the ferromagnetic material being in contact with at least a part of the exterior lateral surface of each of the one or more magnets.

### Claim 3 (depends on 1)

An inductor core according to claim 1, wherein the south pole and the north pole of the first path belong to a single magnet.

### Claim 4 (depends on 3)

An inductor core according to claim 3, wherein the ferromagnetic material completely surrounds the lateral face of each of the one or more magnets, the inductor core comprising two end faces comprising for one the south pole and ferromagnetic material and for the other the north pole and ferromagnetic material, each end face facing a non-magnetic zone designated end non-magnetic zones.

### Claim 5 (depends on 4)

An inductor core according to claim 4, wherein the ferromagnetic material forms a sleeve receiving the one or more magnets and in contact with the exterior lateral surface of the one or more magnets, and wherein distance between the poles of the one or more magnets and magnetic length of the core are equal or substantially equal, the end non-magnetic zones being formed by air.

### Claim 6 (depends on 1)

An inductor core according to claim 1, wherein the south pole and the north pole of the first path belong to distinct magnets, the distinct magnets being arranged such that the poles of opposite polarities of two successive magnets are facing or substantially facing.

### Claim 7 (depends on 6)

An inductor core according to claim 6, wherein the poles facing two magnets are connected by zones of ferromagnetic material.

### Claim 8 (depends on 6)

An inductor core according to claim 6, wherein the body comprises at least one non-magnetic zone, designated an intermediate non-magnetic zone, at a level of each zone of ferromagnetic material separating the poles facing two magnets to prevent the magnetic flux lines coming out of a north pole of a magnet from looping back directly to the south pole of the magnet without preventing the magnetic flux lines from passing from one pole to the other of two successive magnets.

### Claim 9 (depends on 8)

An inductor core according to claim 8, wherein each intermediate non-magnetic zone comprises a cavity.

### Claim 10 (depends on 9)

An inductor core according to claim 9, wherein the cavity emerges in opposite exterior faces of the body.

### Claim 11 (depends on 10)

An inductor core according to claim 10, wherein the cavity is filled with a heat conducting and electrically insulating material.

### Claim 12 (depends on 6)

An inductor core according claim 6, wherein the body has a given thickness, the magnets extending over an entire thickness of the body.

### Claim 13 (depends on 6)

An inductor core according to claim 6, wherein the body comprises a rectangular frame and a central bar arranged transversally with respect to sides of the frame of longest length and parallel to sides of the frame of smallest length, and wherein two first paths are delimited in the frame and in the central bar in a symmetrical manner with respect to a plane of symmetry passing through the central bar and perpendicular to a mean plane of the frame, and two second paths are delimited in the frame and in the central bar in a symmetrical manner with respect to the plane of symmetry and in which the central bar comprises an air gap.

### Claim 14 (depends on 13)

An inductor core according to claim 13, wherein each side of longer length comprises two magnets of same length and each side of smaller length comprising one magnet, and wherein the central bar comprises a magnet on each side of the air gap, such that the two first paths each comprise five magnets.

### Claim 15 (depends on 6)

An inductor core according to claim 6, wherein an air gap is arranged between the end south pole and the end north pole and forming the end non-magnetic zones.

### Claim 16 (depends on 1)

An inductor core according to claim 1, wherein the ferromagnetic material has a permeability less than 100.

### Claim 17 (depends on 1)

An inductor core according to claim 1, wherein the ferromagnetic material is a spinel ferrite selected from NiZn or MnZn.

### Claim 18 (depends on 1)

An inductor comprising an inductor core according claim 1 and a conductor wound around at least one part of the core.

### Claim 19 (depends on 18)

A converter comprising at least one electronic component and at least one inductor according to claim 18.

### Claim 20 (depends on 1)

A method for manufacturing an inductor core according to claim 1, comprising:
a) supplying at least one magnet;
b) manufacturing a body made of ferromagnetic material by injection molding from a feedstock comprising at least one ferromagnetic powder and organic matter, to arrange at least one cavity for mounting of the magnet in the body,
c) mounting the magnet in the cavity.

### Claim 21 (depends on 20)

A method for manufacturing according to claim 20, wherein during b), at least one cavity is produced to form a non-magnetic zone and comprising putting in place a non-magnetic, non-electrically conducting and heat conducting material in the cavity forming the non-magnetic zone.

### Claim 22 (depends on 20)

A method for manufacturing according to claim 20, wherein during a), the magnet is a bonded magnet and the magnet is produced by molding a mixture of at least one magnetic powder and a polymer matrix.

### Claim 23 (depends on 20)

A method for manufacturing according to claim 20, wherein b) comprises molding the feedstock, debinding, and heat treating.