Permanent Magnet Slit Design for Eddy Current Reduction

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Solution Overview

Problem

Current methods for reducing eddy current losses in permanent magnets in permanent magnet machines involve costly segmentation processes, including cutting and gluing, which complicate coating and increase manufacturing costs, and pose health risks due to adhesive handling.

Innovation Solution

A permanent magnet design featuring a base body with slits of varying depths, formed using methods like multi-wire cutting or laser cutting, that eliminates the need for gluing and simplifies the manufacturing process, reducing handling risks and costs while maintaining magnetic performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the permanent magnet is cut into small magnetic pieces and glued back together to reduce eddy current losses, then the eddy current losses are reduced, but the manufacturing cost increases and the manufacturing process becomes more complex

Engineering Contradiction:
Improveeddy current lossesVSAvoidmanufacturing process complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The permanent magnet is divided into multiple segments by cutting slits at different depths from the outer circumference toward the center. The first slit extends to a first depth, the second slit extends to a second depth greater than the first depth, creating a segmented structure that interrupts eddy current paths while maintaining a single-piece construction that eliminates gluing operations

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Instead of cutting the magnet into separate pieces that require assembly in three dimensions, the slits create a layered segmented structure within a single piece. The varying depths of slits create different levels or dimensions of segmentation within the same continuous magnet body, eliminating the need for external gluing while achieving eddy current reduction

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

2Loss of energy

If the permanent magnet is cut into small magnetic pieces and glued back together, then the eddy current losses are reduced, but the manufacturing cost increases

Engineering Contradiction:
Improveeddy current lossesVSAvoidmanufacturing cost
Core Design Contradiction:
Loss of energyVSEase of manufacture

Solution Approach 1:

The multiple slit cutting operations are combined into a single-piece manufacturing process. Instead of cutting separate pieces and gluing them, the magnet is created as one continuous piece with multiple slits of varying depths, merging the segmentation function and the structural integrity into a single manufacturing step that eliminates gluing costs and reduces overall manufacturing complexity

Inventive Principle:
Principle #5Merging (Combining)

3Loss of energy

If the permanent magnet is cut into small magnetic pieces and glued back together, then the eddy current losses are reduced, but the coating quality deteriorates due to different adhesive properties of surfaces

Engineering Contradiction:
Improveeddy current lossesVSAvoidcoating quality
Core Design Contradiction:
Loss of energyVSManufacturing precision

Solution Approach 1:

By maintaining the magnet as a single piece with internal slits rather than assembling multiple pieces, the invention creates a uniform outer surface without glue layers or joints. This unified surface has consistent adhesive properties throughout, allowing for uniform coating application and eliminating the coating quality problems that arise from assembling pieces with different surface characteristics

Inventive Principle:
Principle #5Merging (Combining)

4Loss of energy

If the permanent magnet is cut into small magnetic pieces and glued back together, then the eddy current losses are reduced, but the handling risks and health hazards increase

Engineering Contradiction:
Improveeddy current lossesVSAvoidhandling risks and health hazards
Core Design Contradiction:
Loss of energyVSObject-affected harmful factors

Solution Approach 1:

The invention combines all magnetic segments into a single continuous piece that is held together by the magnet material itself rather than external adhesives. This eliminates the need to handle and apply hazardous gluing materials during manufacturing, reducing health risks and handling hazards while maintaining the eddy current reduction benefits of segmentation

Inventive Principle:
Principle #5Merging (Combining)

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 eddy current losses, lowers manufacturing costs, and simplifies the production process by eliminating the need for gluing, thereby reducing health risks and improving coating quality and lead time.

Implementation Method 1

In today's permanent magnet machines in order to reduce eddy current losses in permanent magnets of a permanent magnet machines

Methodology Applied
Scientific EffectEddy current losses: Eddy Currents

Data Source

PatentEP3457532B1Permanent magnet for a permanent magnet machine
Publication Date: 2023.02.01 SIEMENS GAMESA RENEWABLE ENERGY AS
  • EP3457532B1 patent drawingFigure 1~2
  • EP3457532B1 patent drawingFigure 3~4
  • EP3457532B1 patent drawingFigure 5

AI summary

The present invention describes a permanent magnet (100) for a permanent magnet machine, a permanent magnet machine, and a method of manufacturing a permanent magnet (100) for a permanent magnet machine. The permanent magnet (100) comprises a base body (110) having a first side (131) and a second side (132) which is an opposite side with respect to the first side (131), wherein at least one first slit (121) is formed in the base body (110) such that the at least one first slit (121) extends from the first side (131) in the direction of the second side (132).