Soft magnetic core with position-dependent permeability
View Patent ↗A soft magnetic core is provided, in which permeabilities that occur at least two different locations of the core are different. A method for producing a soft magnetic core that has different permeabilities at at least two different locations is also provided.
1. A method for producing a soft magnetic core with a first portion having a first magnetic permeability and a second portion having a second magnetic permeability, the first magnetic permeability being different from the second magnetic permeability, and a ratio of the first magnetic permeability to the second magnetic permeability being greater than 1:1.1, the method comprising:
providing a magnetic tape having a length and magnetic permeability that increases over the length, and
radially winding the soft magnetic tape to provide a core whose magnetic permeability increases outwardly in a radial direction.
2. The method of claim 1 , further comprising:
subjecting the tape to a heat treatment, and during or after the heat treatment:
exposing the tape to a tensile force in a longitudinal direction of the tape to produce a tensile stress in the tape,
determining the magnetic permeability per section of length of the heat-treated tape after exposing the tape to the tensile force, and
adjusting the tensile force such that the determined permeability for each section of length corresponds to a value of a given permeability profile.
3. The method of claim 2 , further comprising exposing, during or after the heat treatment, the tape to at least one magnetic field.
4. The method of claim 3 , wherein the at least one magnetic field is perpendicular to the longitudinal direction of the tape.
5. The method of claim 1 , further comprising:
placing core powder in a mold; and
at least one of compressing and curing, in the mold, the core powder to provide a powder core element.
6. The method of claim 5 , further comprising winding the tape onto the powder core element.
7. The method of claim 5 , wherein the powder core element is annular.
8. The method of claim 5 , wherein the powder core element has a homogeneous permeability distribution.
9. The method of claim 5 , wherein the powder core element has a permeability that is equal to or smaller than a minimum permeability of the tape.
10. The method of claim 1 , wherein a ratio between a minimum permeability and a maximum permeability of the soft magnetic core is greater than 1:1.2.
11. The method of claim 10 , wherein a ratio between a minimum permeability and a maximum permeability of the soft magnetic core is greater than 1:1.5.
12. The method of claim 11 , wherein a ratio between a minimum permeability and a maximum permeability of the soft magnetic core is greater than 1:2.
13. The method of claim 12 , wherein a ratio between a minimum permeability and a maximum permeability of the soft magnetic core is greater than 1:5.
14. A method for producing a soft magnetic core with a first portion having a first magnetic permeability and a second portion having a second magnetic permeability, the first magnetic permeability being different from the second magnetic permeability, and a ratio of the first magnetic permeability to the second magnetic permeability being greater than 1:1.1, the method comprising:
placing core powder in a mold;
at least one of compressing and curing, in the mold, the core powder to provide a powder core element;
providing a magnetic tape having a length and magnetic permeability that increases over the length, and
radially winding the soft magnetic tape over the powder core element to provide a core whose magnetic permeability increases outwardly in a radial direction.
15. The method of claim 14 , further comprising:
subjecting the tape to a heat treatment, and during or after the heat treatment:
exposing the tape to a tensile force in a longitudinal direction of the tape in order to produce a tensile stress in the tape,
determining the magnetic permeability per section of length of the heat-treated tape after exposing the tape to the tensile force, and
adjusting the tensile force such that the determined permeability for each section of length corresponds to a value of a given permeability profile.
16. The method of claim 15 , further comprising exposing, during or after the heat treatment, the tape to at least one magnetic field.
17. The method of claim 16 , wherein the at least one magnetic field is perpendicular to the longitudinal direction of the tape.
18. The method of claim 14 , wherein the powder core element is annular.
19. The method of claim 14 , wherein the powder core element has a homogeneous permeability distribution.
20. The method of claim 14 , wherein the powder core element has a permeability that is equal to or smaller than a minimum permeability of the tape.