Laminated Core Structure for Electric Motor

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Solution Overview

Problem

Conventional electrical machines using iron-silicon alloy laminations suffer from efficiency and torque output limitations due to saturation issues, with asynchronous machines being less efficient than synchronous machines and having higher production costs, and existing designs do not effectively manage magnetic flux and core losses.

Innovation Solution

The electrical machine employs a stator and rotor lamination structure with distinct regions of different materials and densities, particularly using cobalt-rich materials in areas with higher magnetic flux density to enhance saturation magnetization and reduce core losses, thereby improving the magnetic circuit and increasing torque output and efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional iron-silicon alloy laminations are used throughout the entire electrical machine, then manufacturing cost is reduced and production is simplified, but saturation occurs in high flux density areas which reduces efficiency and limits power output

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidcore loss
Core Design Contradiction:
Ease of manufactureVSLoss of energy

Solution Approach 1:

The patent applies different material qualities to different regions of the electrical machine. Specifically, a first material (conventional iron-silicon alloy) is used in regions with lower magnetic flux density, while a second material with superior magnetic properties (higher saturation magnetization and lower core loss) is used in regions with higher magnetic flux density. This local differentiation optimizes performance where needed while maintaining cost-effectiveness in less critical areas.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent employs a composite lamination structure combining two different materials with distinct magnetic properties. The first material provides cost-effective performance in low flux density regions, while the second material delivers superior magnetic characteristics in high flux density regions. This composite approach allows the electrical machine to achieve enhanced overall performance without the prohibitive cost of using premium materials throughout the entire structure.

Inventive Principle:
Principle #40Composite materials

2Loss of energy

If higher quality magnetic material is used in high flux density areas, then saturation magnetization increases and core loss decreases, but manufacturing complexity and production cost increase

Engineering Contradiction:
Improvecore lossVSAvoidlamination structure complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The patent implements local quality by concentrating the superior magnetic material (second material) specifically in regions experiencing high magnetic flux density, such as tooth portions and bridge areas. The conventional material (first material) is used in regions with lower flux density. This targeted approach reduces core loss in critical areas while avoiding the complexity and cost of using premium materials throughout the entire electrical machine.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The lamination structure is segmented into multiple regions with different material assignments. The electrical machine's core is divided into high flux density regions (requiring second material) and low flux density regions (using first material). This segmentation allows for optimized material placement that balances performance requirements with manufacturing complexity, enabling selective application of high-performance materials only where necessary.

Inventive Principle:
Principle #1Segmentation

3Productivity

If uniform material is used throughout the electrical machine, then production cost is lower and manufacturing is simpler, but efficiency and torque output are limited due to saturation in critical areas

Engineering Contradiction:
Improvepower outputVSAvoidmanufacturing cost
Core Design Contradiction:
ProductivityVSEase of manufacture

Solution Approach 1:

The patent applies local quality by using a second material with higher saturation magnetization specifically in high flux density regions such as tooth portions and bridges, while using a first material in other regions. This localized application of superior magnetic material increases the overall saturation magnetization of the electrical machine, enabling higher power output and torque without the prohibitive cost of using premium materials throughout the entire structure.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent employs composite materials combining a first material (conventional iron-silicon alloy) and a second material (superior magnetic material) in a strategically designed lamination structure. This composite approach enables the electrical machine to achieve enhanced productivity and power output by leveraging the superior magnetic properties of the second material in critical high flux density areas, while maintaining cost-effectiveness through the use of conventional materials in less critical regions.

Inventive Principle:
Principle #40Composite materials

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 increases the saturation magnetization and reduces core losses, leading to enhanced performance and efficiency in electrical machines, particularly in asynchronous machines, without the need for rare earth materials, while maintaining cost-effectiveness.

Implementation Method 1

a first region with a first saturation magnetization and a second region with a second saturation magnetization in a direction perpendicular to the axis of rotation of the electric machine, the second saturation magnetization being higher than the first saturation magnetization

Methodology Applied
Scientific EffectSaturation magnetization: Magnetic Saturation

Implementation Method 2

the stator lamination structure and/or the rotor lamination structure have the first region with a first core loss and the second region with a second core loss, the second core loss being lower than the first core loss

Methodology Applied
Scientific EffectCore loss: Magnetic Hysteresis

Data Source

PatentEP3063855B1Improved electrical laminated core structure for an electric motor
Publication Date: 2022.01.26 BAYERISCHE MOTOREN WERKE AG
  • EP3063855B1 patent drawingFigure 1
  • EP3063855B1 patent drawingFigure 2
  • EP3063855B1 patent drawingFigure 3

AI summary

The invention relates to an electric machine, having a stator, on which a plurality of phase windings is disposed, and which has at least one stator lamination structure which extends perpendicular to the axis of rotation of the electric motor; and a rotor which has at least one rotor lamination structure which extends perpendicular to the axis of rotation of the electric motor; characterised in that the stator lamination structure and/or the rotor lamination structure has, in the direction perpendicular to the axis of rotation of the electric motor, a first region having a first saturation magnetisation and a second region having a second saturation magnetisation, the second saturation magnetisation being higher than the first saturation magnetisation.