Amorphous Alloy Laminated Core Annealing for Lower Iron Loss

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Solution Overview

Problem

Existing methods for magnetic field annealing of laminated cores with amorphous alloy thin strips do not sufficiently reduce iron loss due to differences in magnetic flux direction between the core back and teeth, limiting efficiency in rotating machines.

Innovation Solution

A laminated core design with annular thin pieces of Fe-based amorphous alloy, stacked in a specific orientation, and subjected to magnetic field annealing at controlled temperatures and magnetic fields to create a magnetic domain structure with controlled magnetic domains, reducing iron loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If conventional magnetic field annealing methods are applied to laminated cores, then some iron loss reduction is achieved, but the iron loss cannot be sufficiently reduced due to different magnetic flux directions in core back and teeth

Engineering Contradiction:
Improveiron lossVSAvoidapplicability of annealing method
Core Design Contradiction:
Loss of energyVSAdaptability or versatility

Solution Approach 1:

The patent applies different magnetic field directions to different regions of the laminated core: a first magnetic field in the radial direction for the core back, and a second magnetic field in the axial direction for the teeth. This local differentiation of magnetic field orientation matches the different magnetic flux directions in each region, enabling effective iron loss reduction throughout the entire core structure.

Inventive Principle:
Principle #3Local quality

2Loss of energy

If a single magnetic field direction is applied during annealing, then the process is simple, but iron loss reduction is insufficient for regions with different magnetic flux orientations

Engineering Contradiction:
Improveiron lossVSAvoidannealing process complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The annealing process is segmented into region-specific treatments: the core back receives a first magnetic field in the radial direction, while the teeth receive a second magnetic field in the axial direction. This segmentation allows each region to be treated according to its specific magnetic flux characteristics, maximizing iron loss reduction while maintaining process feasibility.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces multi-dimensional magnetic field orientation by applying magnetic fields in different spatial directions (radial for core back, axial for teeth) rather than a single uniform direction. This dimensional differentiation enables the annealing process to address the three-dimensional complexity of magnetic flux paths in the laminated core structure.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 laminated core achieves significantly reduced iron loss, enhancing the efficiency of rotating machines by optimizing the magnetic domain structure and annealing process.

Implementation Method 1

performing annealing in a magnetic field of a laminated body including a plurality of annular thin pieces including an Fe-based amorphous alloy

Methodology Applied
Scientific EffectMagnetic field annealing: Annealing

Implementation Method 2

create a magnetic domain structure with controlled magnetic domains

Methodology Applied
Scientific EffectMagnetic domain formation: Magnetism

Data Source

PatentEP4683173A1Laminated core, rotating machine, and manufacturing method for laminated core
Publication Date: 2026.01.21 NIPPON STEEL CORPORATION
  • EP4683173A1 patent drawingFigure 1
  • EP4683173A1 patent drawingFigure 2
  • EP4683173A1 patent drawingFigure 3

AI summary

A laminated core includes a plurality of annular thin pieces being stacked in the thickness direction thereof and including an Fe-based amorphous alloy having an amorphous microstructure, and has a ratio (Wθ/Wr) of less than 1.0, the ratio (Wθ/Wr being the iron loss Wθ in the circumferential direction of the thin pieces to the iron loss Wr in the radial direction orthogonal to the circumferential direction and the thickness direction.