Composite Magnetic Core Structure for Better DC Bias
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Solution Overview
Problem
Conventional magnetic devices with metal magnetic powder and resin-based cores face limitations in achieving superior DC bias characteristics, necessitating improved magnetic permeability and energy efficiency.
Innovation Solution
A magnetic core comprising metal magnetic particles with a total area percentage of 75% to 90%, where the particles include large particles with Heywood diameters of 3 μm or more and small particles with diameters less than 3 μm, and the small particles have two or more types of insulating films with different compositions, enhancing magnetic permeability and DC bias characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional metal magnetic powder with single particle size is used, then manufacturing is simple, but DC bias characteristics are insufficient
Solution Approach 1:
The metal magnetic powder is segmented into multiple particle size ranges (first particles: 3 μm or more, second particles: less than 3 μm) to improve DC bias characteristics. This segmentation allows different particle sizes to fill spaces more efficiently and create optimal magnetic pathways, resolving the contradiction between simple manufacturing and superior DC bias performance.
Solution Approach 2:
Different regions of the magnetic core contain particles with different sizes and film compositions. The first particles (larger size) provide structural framework while second particles (smaller size) fill interstitial spaces. Additionally, small particles have two or more types of insulating films with different compositions, creating local variations in electrical and magnetic properties that optimize overall DC bias characteristics.
2Reliability
If total area percentage of metal magnetic particles is increased to improve magnetic permeability, then magnetic permeability improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent optimizes the total area percentage parameter of metal magnetic particles to be 75% or more and 90% or less, and controls the ratio A1/A2 between first and second particles. These parameter changes achieve high magnetic permeability while maintaining manufacturability through defined compositional ranges rather than requiring absolute precision.
Solution Approach 2:
The magnetic core uses a composite structure combining first particles (3 μm or more) and second particles (less than 3 μm) with different insulating film compositions. This composite material approach allows achieving high magnetic permeability through synergistic effects of different particle types, reducing the need for extreme manufacturing precision in any single component.
3Volume of moving object
If miniaturization is pursued for compact magnetic devices, then device size decreases, but DC bias characteristics deteriorate
Solution Approach 1:
The magnetic core structure employs a nested arrangement where second particles (less than 3 μm) are positioned within the interstitial spaces between first particles (3 μm or more). This nested configuration maximizes the density of magnetic material within a compact volume, enabling miniaturization while maintaining high DC bias characteristics through efficient space utilization.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The magnetic core exhibits improved DC bias characteristics and magnetic permeability, enabling more efficient and compact magnetic devices such as inductors, transformers, and choke coils.
Implementation Method 1
the second particles comprise two or more types of small particles with different compositions of films existing on their particle surfaces
Data Source
AI summary
A magnetic core includes metal magnetic particles. A total area percentage of the metal magnetic particles in a cross section of the magnetic core is 75% or more and 90% or less. The metal magnetic particles include first particles whose Haywood diameters in the cross section of the magnetic core are 3 μm or more and second particles whose Haywood diameters in the cross section of the magnetic core are less than 3 μm. The second particles include two or more types of small particles with different compositions of films existing on their particle surfaces.