Grain-Oriented Electrical Steel Sheet Closure Domain Width Control
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Solution Overview
Problem
Conventional methods for reducing eddy current loss in grain-oriented electrical steel sheets through laser or electron beam irradiation often result in increased hysteresis loss and noise, as they form closure domains that increase magnetostriction and strain, leading to suboptimal performance in transformers.
Innovation Solution
The formation of closure domains in a specific width and density range, defined by the inequality −(500t−80)×s+230≤w≤−(500t−80)×s+330, where t is the sheet thickness, w is the width of the closure domains, and s is the average number of regions per crystal grain, effectively reduces both eddy current and hysteresis losses by stabilizing magnetostatic energy and eliminating lancet domains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If closure domains are formed to reduce eddy current loss, then eddy current loss decreases, but noise increases due to increased magnetostriction and strain
Solution Approach 1:
The patent applies partial irradiation by controlling the laser or electron beam to treat only specific regions of the steel sheet, or by using intermittent scanning patterns. This partial action creates closure domains in controlled areas rather than uniformly across the entire sheet, reducing overall noise generation while still achieving significant eddy current loss reduction in the treated regions
Solution Approach 2:
The irradiation is applied periodically with controlled scanning patterns, creating alternating treated and untreated regions. This periodic action allows the formation of closure domains that reduce eddy current loss while the untreated regions provide relief from continuous strain accumulation, thereby reducing noise generation
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 achieves a significant reduction in both eddy current and hysteresis losses, resulting in a grain-oriented electrical steel sheet with low coercive force and noise, enhancing energy efficiency and transformer performance.
Implementation Method 1
irradiation of a laser beam, an electron beam and the like, which may subdivide magnetic domains to reduce eddy current loss
Implementation Method 2
JP H07-65106 B2 (PTL 5) discloses a method for producing an electrical steel sheet having a reduced iron loss W17/50 of below 0.8 W/kg by using electron beam irradiation
Implementation Method 3
magnetic domain refining by applying thermal strain is performed by means of laser irradiation, electron beam irradiation and the like
Implementation Method 4
rapid heating and rapid cooling
Data Source
AI summary
Disclosed is a grain-oriented electrical steel sheet exhibiting low hysteresis loss and low coercive force, in which an increase in hysteresis loss due to laser irradiation or electron beam irradiation, which has been a conventional concern, is effectively inhibited. The grain-oriented electrical steel sheet has closure domain regions (X) formed to divide the magnetic domains in a rolling direction, from one end to the other in the width direction of the steel sheet, provided that Expression (1) is satisfied:−(500t−80)×s+230≤w≤−(500t−80)×s+330 Expression (1),where t represents a sheet thickness (mm); w represents a smaller one of the widths (μm) of the regions measured on the front and rear surfaces of the steel sheet, respectively, by using a Bitter method; and s represents an average number of the regions present within one crystal grain.