Laser-Welded Laminated Core for Low Eddy Current Loss
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Solution Overview
Problem
Existing laminated core production methods face challenges in achieving high performance and efficiency due to limitations in sheet thickness, fill factor, and eddy current losses, particularly in the production of thin layers, which affect the power density and efficiency of electromagnetic machines.
Innovation Solution
The use of laser sublimation cutting to separate lamination sheets from a soft magnetic alloy strip and subsequent laser spot welding with a lapping technique to create a plurality of small, optimally distributed joints within the main surfaces of the laminated core, eliminating burrs and heat-affected zones, and allowing for the stacking of very thin layers with improved resistance to eddy currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional cutting methods are used to separate lamination sheets, then production speed is maintained, but burrs are formed on the edges affecting stacking quality
Solution Approach 1:
The patent replaces mechanical cutting methods with laser sublimation cutting. The laser beam directly sublimates the material at the cutting line without mechanical contact, eliminating burr formation while maintaining high production speed. This substitution of mechanical system with optical/thermal system resolves the contradiction between edge quality and productivity.
Solution Approach 2:
The patent utilizes the phase transition of the soft magnetic alloy from solid directly to vapor (sublimation) through laser heating. This phase transition enables clean material removal without melting and burr formation, achieving both high precision edges and efficient production.
2Loss of energy
If thicker lamination sheets are used, then mechanical stability is improved, but eddy current losses increase
Solution Approach 1:
The patent segments the lamination sheets into very thin individual layers (thinner than conventional sheets) and stacks them with insulation. This segmentation reduces eddy current paths and losses while the large number of stacked layers maintains the overall mechanical stability and strength of the laminated core.
Solution Approach 2:
The patent changes the thickness parameter of the lamination sheets to very thin dimensions, which directly reduces eddy current losses (proportional to square of thickness). The mechanical stability is compensated by increasing the number of layers and using effective joining methods.
3Power
If a high fill factor is achieved, then power density increases, but manufacturing complexity increases
Solution Approach 1:
The patent uses laser sublimation cutting and laser spot welding to replace complex mechanical punching and joining systems. This enables precise control of lamination geometry and joining quality, achieving high fill factors while maintaining manufacturing efficiency and reducing overall system complexity.
Solution Approach 2:
The patent optimizes parameters such as lamination thickness, joint size, and stacking arrangement to maximize the fill factor. By controlling these parameters through laser processing, high power density is achieved without proportionally increasing manufacturing complexity.
4Reliability
If conventional joining methods are used, then production speed is maintained, but joint quality and electrical insulation are compromised
Solution Approach 1:
The patent replaces conventional mechanical joining and insulation methods with laser spot welding. The laser process creates precise, clean joints with controlled heat input, ensuring both electrical insulation and mechanical strength while maintaining high production speed through automated processing.
Solution Approach 2:
The laser spot welding process utilizes controlled melting and resolidification (phase transitions) to create high-quality joints. The rapid heating and cooling cycles produce clean welds with good electrical insulation properties, achieving both reliability and productivity.
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 enables the production of laminated cores with lower eddy current losses and higher output, offering better productivity and mechanical stability, while maintaining the soft magnetic properties, suitable for high-performance drives in medium-sized and mass production series.
Implementation Method 1
separating the lamination sheets from a strip of the soft magnetic alloy by laser sublimation cutting. Since in laser sublimation cutting the material is sublimated or evaporated at the cutting line
Implementation Method 2
the material is sublimated or evaporated at the cutting line in order to sever the material
Implementation Method 3
These joints may, for example, be formed of resolidified molten material of the lamination sheets and be formed by a process such as welding, e.g. spot welding or laser spot welding
Data Source
AI summary
A method for producing a laminated core is provided in which a plurality of lamination sheets is partially or completely separated from a strip made of a soft magnetic alloy by laser sublimation cutting, the lamination sheets each having a main surface and a thickness d. The main surface of a first of the lamination sheets is stacked on the main surface of a second of the lamination sheets in a direction of stacking and the main surfaces of the first and the second lamination sheets are substance-to-substance joined at a plurality of points by laser welding, a plurality of filler-free joints being formed between the between the first and the second lamination sheets and being entirely surrounded by the main surfaces of the first and the second lamination sheets.