Oriented Electromagnetic Steel Plate Noise Reduction
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Solution Overview
Problem
Grain oriented electrical steel sheets, despite magnetic domain refinement treatments, generate significant noise when used in transformers due to differences in magnetic domain widths between treated and untreated surfaces, leading to high-harmonic components in magnetostrictive vibrations.
Innovation Solution
Applying strain introduction techniques like electron beam or continuous laser irradiation to both sides of the steel sheet to achieve uniform magnetic domain refinement, ensuring a magnetic flux density of 1.92 T or higher, and maintaining the tension coating integrity to reduce noise by minimizing differences in magnetic domain widths and discontinuous portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If magnetic domain refinement treatment is applied to reduce iron loss, then iron loss is reduced, but noise increases due to non-uniform magnetic domain width
Solution Approach 1:
The patent applies local quality by performing magnetic domain refinement treatment on both surfaces of the steel sheet uniformly. This ensures that the magnetic domain width is controlled locally at each surface, creating consistent properties throughout the material thickness, which reduces noise while maintaining low iron loss.
Solution Approach 2:
The patent changes the parameter of magnetic domain width uniformly across both surfaces through controlled refinement treatment. By adjusting the treatment conditions to achieve specific magnetic domain width ranges (5-20 μm on each surface), the patent simultaneously optimizes both iron loss and noise characteristics.
2Manufacturing precision
If electron beam or laser irradiation is used for magnetic domain refinement, then magnetic domain width is reduced, but non-uniformity between treated and untreated surfaces increases
Solution Approach 1:
The patent segments the treatment approach by applying magnetic domain refinement independently to both surfaces of the steel sheet. This segmentation allows each surface to be treated uniformly, ensuring consistent magnetic domain structure throughout the material and eliminating non-uniformity between treated and untreated surfaces.
Solution Approach 2:
The patent employs periodic action by applying alternating current excitation at standard frequencies (50-60 Hz) to induce magnetostrictive vibration that uniformly refines magnetic domains across both surfaces. This periodic treatment ensures consistent magnetic domain structure without creating local non-uniformities.
3Loss of energy
If strain introduction is applied to one side only, then iron loss is reduced, but magnetostrictive vibration becomes non-uniform causing high noise
Solution Approach 1:
The patent applies local quality by introducing strain uniformly on both surfaces of the steel sheet through magnetic domain refinement treatment. This creates consistent local properties throughout the material, ensuring uniform magnetostrictive behavior and reducing noise while maintaining iron loss reduction benefits.
Solution Approach 2:
The patent addresses asymmetry by explicitly treating both surfaces of the steel sheet with magnetic domain refinement, rather than treating only one surface. This symmetric treatment approach eliminates the asymmetry that would otherwise cause non-uniform magnetostrictive vibration and high noise levels.
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 solution effectively reduces transformer noise by ensuring identical magnetic domain refinement on both sides, resulting in lower iron loss and less high-harmonic components, thereby reducing noise levels to 40.0 dBA or less.
Implementation Method 1
applying strain introduction techniques like electron beam or continuous laser irradiation to both sides of the steel sheet
Implementation Method 2
applying strain introduction techniques like electron beam or continuous laser irradiation to both sides of the steel sheet
Implementation Method 3
the noise of a transformer is caused by the magnetostrictive behavior occurring when an electrical steel sheet is magnetized
Data Source
Figure 1
AI summary
A grain oriented electrical steel sheet having a magnetic domain structure modified by strain introduction without a trace of treatment, in which noise generated when the grain oriented electrical steel sheet is used laminated on an iron core of a transformer is effectively reduced by: setting a magnetic flux density B8 to 1.92 T or higher; then setting a ratio of average magnetic domain width of treated surface after strain-introducing treatment Wa to average magnetic domain width before strain-introducing treatment W0 as Wa/W0 < 0.4; and setting a ratio of Wa to average magnetic domain width of untreated surface Wb as Wa/Wb > 0.7; and further setting a ratio of average width of magnetic domain discontinuous portion Wd in the untreated surface to average width of magnetic domain discontinuous portion in treated surface resulting from strain-introducing treatment Wc as Wd/Wc > 0.8; and setting Wc < 0.35 mm.