Magnetic Core Coating Ratio for Low Core Loss and DC Bias
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Solution Overview
Problem
Existing magnetic cores with metal magnetic powders face challenges in reducing core loss while maintaining good DC bias characteristics, particularly when using a combination of amorphous and nanocrystalline structures, as simple mixing of these structures does not effectively lower core loss and improve magnetic permeability simultaneously.
Innovation Solution
A magnetic core with a total area ratio of metal magnetic particles at 75% or more, comprising first large particles with an amorphous structure and second large particles with a nanocrystalline structure, where the insulation coating of the first large particles is thicker than that of the second large particles, optimizing the ratio of their thicknesses to achieve reduced core loss and improved magnetic permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-pressure molding is performed to increase Bs of the magnetic core, then magnetic permeability is improved, but core loss increases due to higher stress required for high-density packing
Solution Approach 1:
The invention changes the material composition parameter by using a specific mixture ratio of amorphous alloy powder (80-95 wt%) and nanocrystalline alloy powder (5-20 wt%), and controls the insulation coating thickness ratio (T1/T2 = 1.3 to 40) between the two particle types. This parameter optimization allows achieving high magnetic permeability without requiring excessive high-pressure molding that would increase core loss.
Solution Approach 2:
The invention uses a composite material system combining amorphous alloy particles with nanocrystalline alloy particles in a specific ratio. The amorphous phase provides high saturation magnetic flux density while the nanocrystalline phase contributes to low core loss, creating a synergistic effect that resolves the contradiction between magnetic permeability and core loss.
2Ease of manufacture
If simple mixing of amorphous and nanocrystalline structures is used, then material processing is simplified, but core loss is not effectively reduced and magnetic permeability is not improved simultaneously
Solution Approach 1:
The invention applies local quality by differentiating the insulation coating thickness between amorphous particles (T1) and nanocrystalline particles (T2), with T1/T2 ratio controlled at 1.3 to 40. This localized differentiation in coating thickness optimizes the buffer effect and magnetic properties of each particle type, achieving effective core loss reduction while maintaining ease of manufacture through a systematic mixing approach.
3Quantity of substance
If amorphous material with high Bs is used, then saturation magnetic flux density increases, but hysteresis loss increases due to higher magnetostriction influence requiring higher stress
Solution Approach 1:
The invention introduces nanocrystalline alloy particles as an intermediary element that mediates between the high saturation magnetic flux density of amorphous material and the low hysteresis loss requirement. The nanocrystalline particles have lower magnetostriction, reducing the overall stress requirement during molding and decreasing hysteresis loss while the amorphous particles maintain high saturation magnetic flux density.
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 approach effectively reduces core loss while maintaining good DC bias characteristics, with the magnetic permeability improved by adjusting the insulation coating thickness ratio, achieving a balance between low core loss and high magnetic performance.
Implementation Method 1
Each of the metal magnetic particles includes an insulation coating
Implementation Method 2
first large particles having an amorphous structure and having a Heywood diameter of 3 μm or more on the cross-section of the magnetic core, and second large particles having a nanocrystal structure
Implementation Method 3
when using an amorphous material with high Bs, since an influence of magnetostriction is higher and a higher stress is required to perform high-density packing
Data Source
AI summary
Provided is a magnetic core containing metal magnetic particles. A total area ratio occupied by the metal magnetic particles on a cross-section of the magnetic core is 75% or more. The metal magnetic particles include first large particles having an amorphous structure and having a Heywood diameter of 3 μm or more on the cross-section of the magnetic core, and second large particles having a nanocrystal structure and having a Heywood diameter of 3 μm or more on the cross-section of the magnetic core. An insulation coating of the first large particles is thicker than an insulation coating of the second large particles.