Printed Laminated Core Structure for Lower Eddy Current Loss
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Solution Overview
Problem
Conventional laminated cores in electrical machines suffer from high eddy current losses, limiting their efficiency and compactness, especially in high-frequency applications like electric vehicles, where thinner magnetic sheets are technically exhausted.
Innovation Solution
A method involving stencil printing to produce thin magnetic sheets with inorganic non-metallic insulating layers, which are sintered together to form a monolithic structure with reduced eddy current losses, allowing for thinner magnetic sheets and improved power density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional punched magnetic sheets are used, then manufacturing is simple and reproducible, but the minimum thickness is limited to 300 μm which increases eddy current losses
Solution Approach 1:
The patent replaces the mechanical punching process with a stencil printing process to create magnetic sheets. This substitution enables precise thickness control at the micrometer level (50-200 μm) without the minimum thickness limitation of punching, thereby reducing eddy current losses while maintaining manufacturing feasibility.
Solution Approach 2:
The patent changes the manufacturing parameter from punched thickness (minimum 300 μm) to printed thickness (50-200 μm), achieving thinner magnetic sheets that reduce eddy current losses. The printing process allows continuous thickness adjustment within this range, providing optimized parameters for high-frequency applications.
2Loss of energy
If magnetic sheet thickness is reduced to decrease eddy current losses, then motor efficiency improves, but manufacturing complexity increases
Solution Approach 1:
The patent replaces the simple but thickness-limited punching process with a stencil printing process that enables thinner sheets. Although printing is more complex than punching, it provides the necessary thickness control (50-200 μm) to reduce eddy current losses, making the increased manufacturing complexity worthwhile for achieving lower energy losses.
Solution Approach 2:
The patent uses a composite structure consisting of magnetic paste layers combined with organic binder materials in the stencil printing process. This composite approach enables the creation of thin, flexible magnetic sheets with controlled properties, facilitating manufacturing of thinner sheets while maintaining ease of production through the printing methodology.
3Power
If thinner magnetic sheets are used, then power density increases and installation space decreases, but eddy current suppression becomes more difficult
Solution Approach 1:
The patent segments the magnetic core into extremely thin individual sheets (50-200 μm) printed from magnetic paste. This segmentation interrupts eddy current paths more effectively than conventional thicker sheets, suppressing eddy current losses while enabling higher power density through the use of thinner, more numerous laminations.
Solution Approach 2:
The patent introduces an organic binder as an intermediary material within the printed magnetic sheet structure. This binder acts as an internal insulating layer that further suppresses eddy currents within the sheet itself, complementing the traditional inorganic insulating layers between sheets and providing enhanced eddy current suppression for high-power-density applications.
4Length of moving object
If stencil printing process is used to produce thin magnetic sheets, then sheet thickness can be reduced to 50-200 μm, but manufacturing process complexity increases
Solution Approach 1:
The patent substitutes the simple punching mechanism with a stencil printing system that uses screens, squeegees, and magnetic paste. This mechanical substitution enables precise thickness control (50-200 μm) that punching cannot achieve, accepting the increased device complexity as necessary to obtain the required thin sheet dimensions for low eddy current losses.
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 method results in laminated cores with lower eddy current losses, enabling smaller installation space and higher power density in electrical machines, particularly suitable for high-frequency applications in electric vehicles.
Implementation Method 1
printing a magnetic green body using a ferrous printing paste by means of a stencil printing process onto a substrate
Implementation Method 2
applying an inorganic, non-metallic insulating layer in a green state to a surface of the magnetic sheet green body
Implementation Method 3
the stencil is usually applied to a screen with a very fine mesh size, and the printing paste is pressed through this screen onto the substrate using the squeegee. To improve the rheological properties during the printing process
Implementation Method 4
During sintering, particles of the individual components of the green body sinter together, particularly through diffusion processes, to form a monolithic, ideally pore-free structure
Implementation Method 5
particles of the individual components of the green body sinter together, particularly through diffusion processes
Implementation Method 6
Debinding means the evaporation or burnout of binders, i.e. the auxiliary materials required for shaping the green body
Implementation Method 7
Debinding means the evaporation or burnout of binders
Implementation Method 8
In this way, a stack of green magnetic sheets and green insulating layers is created
Data Source
Figure 1~2
Figure 3a~3f
Figure 4a~4d
AI summary
The invention relates to a method for manufacturing a lamination stack (2) of an electric machine (4), comprising the following steps: a) printing a magnetic lamination green body (6) using an iron-containing printing paste (8) by means of a stencil printing process (10) onto a substrate (12), b) applying an inorganic, non-metallic insulating layer (14) in a green state to a surface (16) of the magnetic lamination green body (6), c) printing a second magnetic lamination green body (6'), d) applying a second insulating layer (14') in a green state to an uncovered surface (16') of the second magnetic lamination green body (6'), e) applying the second magnetic lamination green body (6') to the insulating layer (14) of the first magnetic lamination green body, f) producing a lamination stack green body (18) by repeating steps a) to e), g) sintering (20) the lamination stack green body (18) to form the lamination stack (2) with alternating magnetic sheets (24) and insulating layers (26).