Grain-Oriented Electrical Steel Stress Patterning for Low Iron Loss

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Solution Overview

Problem

Current grain-oriented electrical steel sheets face challenges in achieving low iron loss and low magnetostriction simultaneously, leading to increased transformer energy loss and noise, as existing methods either increase iron loss or magnetostriction due to strain introduction techniques.

Innovation Solution

The technique involves forming a grain-oriented electrical steel sheet with a linear strain portion by vibrating the sheet in the thickness direction during electron beam irradiation, creating a stress distribution with alternating compressive and tensile stress regions, which reduces iron loss and magnetostriction by enhancing the magnetoelastic effect.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If strain introduction techniques are used to reduce iron loss, then iron loss is reduced, but magnetostriction increases

Engineering Contradiction:

Improveiron lossVSAvoidmagnetostriction

Core Design Contradiction:

Loss of energyVSObject-generated harmful factors

Solution Approach 1:

The invention changes the parameters of strain introduction by controlling the electron beam irradiation conditions (acceleration voltage, beam current, irradiation speed, irradiation pattern) to introduce strain at optimal levels that reduce iron loss while keeping magnetostriction low. This involves precise control of irradiation dose and distribution to achieve the right balance between iron loss reduction and magnetostriction control.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention applies strain introduction locally through selective electron beam irradiation of specific regions of the steel sheet, particularly focusing on the grain boundary regions. This local strain introduction targets the magnetic domain structure at grain boundaries without uniformly straining the entire sheet, thereby reducing iron loss while minimizing overall magnetostriction.

Inventive Principle:

Principle #3Local quality

2Loss of energy

If electron beam irradiation is used to introduce strain, then iron loss is reduced, but production complexity increases

Engineering Contradiction:

Improveiron lossVSAvoidproduction complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The invention replaces traditional mechanical strain introduction methods (such as rolling or pressing) with electron beam irradiation. This substitution allows for more precise and controlled strain introduction without the complexity of mechanical device adjustments, as the electron beam can be precisely controlled through electrical parameters alone.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention simplifies production by controlling strain introduction through changes in electron beam parameters (acceleration voltage, beam current, irradiation speed) rather than requiring complex mechanical setup changes. This makes the process more adaptable and easier to control during production.

Inventive Principle:

Principle #35Parameter changes

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 method effectively reduces energy loss and noise in transformers by forming a closure domain with reduced strain, achieving lower iron loss and magnetostriction while maintaining high magnetic flux density.

Implementation Method 1

When a grain-oriented electrical steel sheet is irradiated with an electron beam, a part irradiated with the electron beam is rapidly heated locally

Methodology Applied

Scientific EffectElectromagnetic energy conversion to thermal energy: Dielectric Heating

Implementation Method 2

thermal strain is formed as a result of thermal expansion and thermal contraction

Methodology Applied

Scientific EffectThermal expansion and contraction: Thermal Expansion

Implementation Method 3

This causes the formation of a magnetic domain (closure domain) having a magnetization direction in the sheet transverse direction, and magnetic domains are refined and the iron loss decreases

Methodology Applied

Scientific EffectMagnetoelastic effect: Magnetoelastic Effects

Data Source

PatentUS11866796B2Grain-oriented electrical steel sheet and production method therefor

Publication Date: 2024.01.09 JFE STEEL CORP

AI summary

Provided is a grain-oriented electrical steel sheet that combines low iron loss and low magnetostriction, together with an advantageous production method therefor. A grain-oriented electrical steel sheet comprises a linear strain portion extending in a direction intersecting a rolling direction of the grain-oriented electrical steel sheet, wherein the linear strain portion has a stress distribution in which a compressive stress region and a tensile stress region alternate in a longitudinal direction of the linear strain portion. The linear strain portion is formed by vibrating the grain-oriented electrical steel sheet in a sheet thickness direction, while irradiating a surface of the grain-oriented electrical steel sheet with an electron beam by repeatedly moving and detaining the electron beam in the direction intersecting the rolling direction of the grain-oriented electrical steel sheet.