Soft Magnetic Powder Grading for Dense Low-Loss Magnetic Cores
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Solution Overview
Problem
Existing soft magnetic metal powders used in magnetic cores face challenges in achieving improved DC superimposition characteristics due to increased core losses and difficulties in increasing dust core density during molding.
Innovation Solution
A soft magnetic metal powder with specific particle size distribution characteristics, including a D50 of 3.0 μm or more and 30.0 μm or less, and a (y95/y50−y90/y50)/(0.95−0.90) ratio of 20.0 or less, is used to manufacture magnetic cores with enhanced DC superimposition characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If amorphous alloy powder is used to reduce core losses, then core losses are reduced, but it becomes difficult to increase the density of the dust core at the time of molding
Solution Approach 1:
The patent uses a composite material consisting of amorphous alloy magnetic powder (70-90 wt%) combined with crystalline alloy magnetic powder (10-30 wt%). This composite approach allows the dust core to achieve both low core losses (from the amorphous component) and high molding density (from the crystalline component that packs more efficiently), thereby resolving the contradiction between energy loss reduction and manufacturing precision.
Solution Approach 2:
The patent changes the particle size parameters of the magnetic powder, specifically controlling the D50 (median diameter) to be within 3.0-30.0 μm and the sphericity to be 0.90 or more. These parameter optimizations improve the flowability and packing characteristics of the powder, enabling higher dust core density during molding while maintaining the low core loss properties of amorphous alloy.
2Ease of manufacture
If metal magnetic powder is used for dust core, then manufacturing is simplified, but core losses are readily increased
Solution Approach 1:
The patent employs a composite magnetic powder material combining amorphous alloy (providing low core losses) with crystalline alloy (maintaining manufacturing ease). This composite formulation preserves the simplicity of dust core manufacturing processes while significantly reducing core losses compared to conventional metal magnetic powders, thus resolving the contradiction between ease of manufacture and energy loss.
3Reliability
If particle size distribution is optimized to improve DC superimposition characteristics, then DC superimposition characteristics are improved, but particle size control complexity increases
Solution Approach 1:
The patent establishes specific parameter ranges for particle size distribution: D50 between 3.0-30.0 μm, sphericity of 0.90 or more, and a controlled particle size distribution where 90-95% of particles fall within a narrow size range. These well-defined parameter specifications simplify the manufacturing process by providing clear targets for particle size control, thereby improving DC superimposition characteristics without excessively increasing control complexity.
Data Source
AI summary
A soft magnetic metal powder includes soft magnetic metal particles with a particle size of 5.0 μm or more. (y95/y50−y90/y50)/(0.95−0.90) is 20.0 or less, where y95 (μm) denotes D95, y90 (μm) denotes D90, and y50 (μm) denotes D50 of a particle size distribution of the soft magnetic metal particles with a particle size of 5.0 μm or more. A magnetic core includes soft magnetic metal particles with a Heywood diameter of 5.0 μm or more in a section of the magnetic core. (Y95/Y50−Y90/Y50)/(0.95−0.90) is 20.0 or less, where Y95 (μm) denotes D95, Y90 (μm) denotes D90, and Y50 (μm) denotes D50 of a particle size distribution of the soft magnetic metal particles with a Heywood diameter of 5.0 μm or more.