Stator Lamination Cooling Channels for Power Density
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Solution Overview
Problem
Existing cooling systems for electric motors and generators, such as press or shrink fitted cooling jackets, increase machine dimensions and suffer from inefficient heat dissipation due to thermal resistance, limiting power density and downsizing potential.
Innovation Solution
A stack of laminations for the stator with geometrically different holes forming axially extending cooling channels, creating complex geometries that promote turbulent fluid flow and enhance heat transfer, optionally including impingement elements to further deflect the cooling fluid, thereby improving heat dissipation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If press or shrink fitted cooling jackets are used to cool the stator, then cooling effect is achieved, but the overall dimensions of the machine increase
Solution Approach 1:
The cooling channels are integrated directly into the stator laminations by forming holes within the lamination structure itself. This merges the cooling system with the stator core, eliminating the need for separate external cooling jackets and thereby reducing the overall machine dimensions while maintaining effective cooling.
Solution Approach 2:
The cooling channels are nested within the stator lamination structure. The holes are formed inside the laminations and aligned axially to create internal cooling passages, allowing the cooling system to be contained within the existing stator footprint without increasing external dimensions.
2Temperature
If press or shrink fitted cooling jackets are used, then cooling is provided, but thermal resistance between stator and cooling jacket increases heat dissipation time
Solution Approach 1:
By integrating the cooling channels directly into the stator laminations, the thermal interface between the stator and cooling system is eliminated. The cooling fluid flows through holes formed within the lamination material itself, creating direct thermal contact between the heat-generating stator core and the cooling fluid, thereby minimizing thermal resistance and accelerating heat dissipation.
Solution Approach 2:
The lamination material itself serves as the thermal conduit between the heat-generating regions and the cooling fluid. The holes are formed within the lamination structure, making the lamination material the direct intermediary for heat transfer, eliminating the need for separate thermal interfaces and reducing overall thermal resistance.
3Temperature
If geometrically different holes are used to form cooling channels, then heat transfer efficiency increases, but manufacturing complexity increases
Solution Approach 1:
The cooling channel is segmented into multiple discrete holes formed in each lamination. Each hole can have different geometries (varying in size, shape, or orientation) to optimize local heat transfer characteristics. This segmentation allows independent optimization of each hole's geometry while maintaining overall manufacturing feasibility through standardized lamination production processes.
Solution Approach 2:
Different holes within the lamination stack have different geometries tailored to local heat transfer requirements. The holes may vary in diameter, shape, or axial orientation depending on the specific thermal conditions at different radial or axial positions in the stator. This local quality optimization enhances overall heat transfer efficiency while each individual hole remains manufacturable using standard processes.
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 increases power density by enhancing heat transfer between the laminations and the cooling fluid, reducing thermal resistance and machine dimensions, while maintaining efficient cooling without the need for additional cooling jackets.
Implementation Method 1
better heat transfer between the laminations and the cooling fluid
Implementation Method 2
turbulent flow of the cooling fluid flowing in the cooling channel
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The present invention relates to a stack (3) of laminations (8, 9) for a stator (4) of an electric machine (1), wherein each lamination (8, 9) comprises a plurality of teeth (6), and a plurality of holes (22, 23), wherein the laminations (8, 9) are aligned relatively to one other such that - the teeth (6) form winding spaces (30) for receiving stator windings, and - the holes (22, 23) form at least one axially extending cooling channel (25, 35) inside the stack (3), wherein adjacent holes (22, 23) of at least two adjacent laminations (8, 9) are geometrically different.