Composite magnetic core for switch-mode power converters
First Claim
1. A magnetic core, comprising:
- a base;
first and second legs on the base and separated from each other;
a center leg on the base and separated from said first and second legs; and
a plate on said first, second and center legs opposite the base,wherein a portion of at least one of said base, center leg and said plate comprises a first material having a first magnetic permeability (μ
rel1) and a first saturation flux density (BSAT1) and the remaining portion of the magnetic core comprises a second material having a second magnetic permeability (μ
rel2) greater than the first by at least a factor of 10.
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Accused Products
Abstract
A composite magnetic core formed of a high permeability material and a lower permeability, high saturation flux density material prevents core saturation without an air gap and reduces eddy current losses and loss of inductance. The composite core is configured such that the low permeability, high saturation material is located where the flux accumulates from the high permeability sections. The presence of magnetic material having a relatively high permeability keeps the flux confined within the core thereby preventing fringing flux from spilling out into the winding arrangement. This composite core configuration balances the requirements of preventing core saturation and minimizing eddy current losses without increasing either the height or width of the core or the number of windings.
222 Citations
21 Claims
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1. A magnetic core, comprising:
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a base; first and second legs on the base and separated from each other; a center leg on the base and separated from said first and second legs; and a plate on said first, second and center legs opposite the base, wherein a portion of at least one of said base, center leg and said plate comprises a first material having a first magnetic permeability (μ
rel1) and a first saturation flux density (BSAT1) and the remaining portion of the magnetic core comprises a second material having a second magnetic permeability (μ
rel2) greater than the first by at least a factor of 10. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A magnetic core, comprising:
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a base; first and second legs on the base and separated from each other; a center leg on the base and separated from said first and second legs; and a plate on said first, second and center legs opposite the base, a plurality of windings around the first and second legs that when energized generate flux that adds together at a location in the base, center leg and said plate; wherein a portion of at least one of said base, center leg and said plate at said location comprises a first material having a first saturation flux density (BSAT1) and a first magnetic permeability (μ
rel1) and the remaining portion of the magnetic core comprises a second material having a second magnetic permeability (μ
rel2) greater than the first by at least a factor of 10.
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17. A magnetic core, comprising:
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a base; first and second legs on the base and separated from each other; a center leg on the base and separated from said first and second legs; and a plate on said first, second and center legs opposite the base, wherein a portion of said center leg comprises a first material having a first saturation flux density (BSAT1) and a first magnetic permeability (μ
rel1) and the remaining portion of the magnetic core comprises a second material having a second magnetic permeability (μ
rel2) greater than the first by at least a factor of 10 anda plurality of primary and secondary windings around the first and second legs that when energized produce a transformer flux component that circulates around the first and second legs, base and plate in a high permeability path and inductor flux components that circulate around said first or second legs, the base, the center leg and the plate in a low permeability path and add together in said portion of said center leg.
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18. A magnetic core, comprising:
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a base; a plurality of outer legs located along a first outer edge of the base and separated from each other a center leg on the base and located along an opposite outer edge of the base and separated from the outer legs; and a plate on said outer and center legs opposite the base, a plurality of windings around the outer legs that when energized generate flux that adds together in the base, center leg and said plate; wherein a portion of at least one of said base, center leg and said plate at said location comprises a first material having a first saturation flux density (BSAT1) and a first magnetic permeability (μ
rel1) and the remaining portion of the magnetic core comprises a 3 second material having a second magnetic permeability (μ
rel2) greater than the first by at least a factor of 10.
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19. A magnetic core, comprising:
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a base; a plurality of outer legs located along a first outer edge of the base and separated from each other a center leg on the base and located along an opposite outer edge of the base and separated from the outer legs; and a plate on said outer and center legs opposite the base, wherein a portion of said center leg comprises a first material having a first saturation flux density (BSAT1) and a first magnetic permeability (μ
rel1) and the remaining portion of the magnetic core comprises a second material having a second magnetic permeability (μ
rel2) greater than the first by at least a factor of 10;a plurality of primary and secondary windings around the outer legs that when energized produce a transformer flux component that circulate around said outer legs, base and plate in a high permeability path and inductor flux components that circulate around said outer legs, the base, the center leg and the plate in a low permeability path and add together in said portion of said center leg. - View Dependent Claims (20, 21)
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Specification