Grain-Oriented Electrical Steel Closure Domain Control for Low Iron Loss
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Solution Overview
Problem
Current methods for measuring the three-dimensional distribution of closure domains in grain-oriented electrical steel sheets are inadequate, leading to difficulties in optimizing their distribution for reduced iron loss and magnetostriction, which are essential for improving transformer performance.
Innovation Solution
The introduction of localized thermal strain in the non-heat-resistant type magnetic domain refining process, using an energy beam orthogonal to the rolling direction, controls the distribution of closure domains, allowing for accurate estimation and optimization of their width and formation interval to minimize iron loss and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If closure domains are introduced to reduce eddy current loss, then eddy current loss decreases, but magnetostriction increases due to strain introduction
Solution Approach 1:
The patent introduces closure domains through localized energy beam irradiation at controlled intervals, creating local thermal strain regions. This localized approach reduces eddy current loss by refining magnetic domains while limiting the overall strain distribution to control magnetostriction increases.
Solution Approach 2:
The patent applies partial action by using controlled energy beam irradiation with specific irradiation intervals, introducing just enough thermal strain to form closure domains for eddy current loss reduction without excessive strain that would cause significant magnetostriction. The irradiation amount is optimized to achieve the minimum necessary effect.
2Measurement precision
If existing measurement methods are used to observe closure domains, then some domain information is obtained, but accurate three-dimensional distribution understanding is insufficient
Solution Approach 1:
The patent transitions from two-dimensional surface observation to three-dimensional distribution understanding by using energy beam irradiation that penetrates through the steel sheet thickness. This allows thermal strain to be introduced and closure domains to form throughout the thickness direction, enabling accurate estimation of three-dimensional distribution rather than just surface characteristics.
Solution Approach 2:
The patent uses energy beam irradiation as an intermediary method to indirectly measure and understand closure domain distribution. By observing the effects of thermal strain introduction and closure domain formation through controlled irradiation, the patent achieves accurate three-dimensional distribution understanding without direct observation limitations.
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 effectively reduces iron loss and noise in transformers by controlling the closure domain width and formation interval, resulting in a grain-oriented electrical steel sheet with improved transformer characteristics.
Implementation Method 1
The introduction of localized thermal strain in the non-heat-resistant type magnetic domain refining process, using an energy beam orthogonal to the rolling direction
Implementation Method 2
a magnetic flux density B-magnetostriction waveform λ, referred to as a butterfly curve, when excited to 1.5 T or more
Data Source
AI summary
Disclosed is a grain-oriented electrical steel sheet that exhibits excellent transformer characteristics and that has low iron loss and low magnetostriction properties. The grain-oriented electrical steel sheet has a magnetic flux density B-magnetostriction waveform λ, referred to as a butterfly curve, when excited to 1.5 T or more, such that an amount of steel sheet elongation (Δλ) with a magnetic flux density B ranging from 1.0 T to 1.5 T is 0.010×10−6 or more and 0.240×10−6 or less, and a length of a closure domain in the rolling direction, referred to as a closure domain width, is 20 μm or more and 240 μm or less.