Non-oriented Electrical Steel Sheet High-Frequency Permeability
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Solution Overview
Problem
Non-oriented electrical steel sheets face limitations in achieving high magnetic permeability at high frequencies due to the width of magnetic domains and the speed of domain wall movement, which restricts their application in energy-efficient devices.
Innovation Solution
The development of a non-oriented electrical steel sheet with controlled alloy composition and precipitates, including Si, Al, S, Mn, N, Cu, and O, where the number of sulfides exceeds nitrides in the base portion and oxides in the surface portion, with specific diameters and concentrations, to reduce domain width and enhance domain wall movement speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If non-oriented electrical steel sheet is used for high frequency applications, then the device can operate at higher frequencies, but the magnetic permeability is insufficient due to wide magnetic domains and slow domain wall movement
Solution Approach 1:
The patent applies parameter changes by precisely controlling the composition and size of precipitates (carbides, nitrides, sulfides, oxides) in the steel sheet. By adjusting the types and dimensions of these precipitates, the magnetic domain width is reduced and domain wall movement speed is increased, thereby improving magnetic permeability at high frequencies while maintaining material reliability
Solution Approach 2:
The patent uses composite material principles by creating a multi-phase microstructure with different types of precipitates (carbides, nitrides, sulfides, oxides) distributed throughout the steel matrix. This composite structure at the micro-scale enables simultaneous optimization of domain wall movement and magnetic permeability, resolving the contradiction between speed and reliability
2Reliability
If magnetic domain width is reduced to increase domain wall movement speed, then high frequency magnetic permeability improves, but the manufacturing complexity increases due to precise control requirements of precipitates
Solution Approach 1:
The patent simplifies manufacturing complexity by establishing specific parameter ranges for precipitate composition and size that can be achieved through conventional steelmaking processes. By defining clear compositional windows for carbides, nitrides, sulfides, and oxides, the patent enables precise control of magnetic properties without requiring complex manufacturing steps
Solution Approach 2:
The patent applies local quality by creating specific precipitate distributions in different regions of the steel sheet (surface portion vs. base portion). This localized control of precipitate types and concentrations allows optimization of magnetic properties in specific areas while maintaining overall manufacturing simplicity through standardized processing
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
This approach results in significantly improved magnetic permeability at high frequencies, with relative magnetic permeability exceeding 8,000 at 50 Hz, 4,000 at 400 Hz, and 2,000 at 1000 Hz, enhancing energy efficiency in devices like motors and generators.
Implementation Method 1
Magnetization occurs as a mechanism in which the magnetic domain wall in the material moves and aligns in the direction of the external magnetic field
Implementation Method 2
the non-oriented electrical steel sheet is composed of a surface portion up to 2 μm from the surface of the steel sheet in the thickness direction and a base portion over 2 μm from the surface of the steel sheet in the thickness direction, and wherein the number of surfides having a diameter of 10 nm to 100 nm is larger than the number of the nitrides having a diameter of 10 nm to 100 nm, in the same area of base portion
Data Source
AI summary
The non-oriented electrical steel sheet according to one embodiment of the present invention includes: by weight, 2.0% to 4.0% of Si; 0.001% to 2.0% of Al; 0.0005% to 0.009% of S; 0.02% to 1.0% of Mn, 0.0005% to 0.004% of N; 0.004% or less of C (excluding 0%); 0.005% to 0.07% of Cu; 0.0001% to 0.007% of O; individually or in a total amount of 0.05% to 0.2% of Sn or P; and the remainder comprising Fe and impurities; wherein the non-oriented electrical steel sheet is composed of a surface portion to 2 μm from the surface of the steel sheet in the thickness direction and a base portion exceeding 2 μm from the surface of the steel sheet in the thickness direction, and wherein the number of surfides having a diameter of 10 nm to 100 nm is larger than the number of the nitrides having a diameter of 10 nm to 100 nm, in the same area of base portion.