Airgap Cooling Manifold Layout for High-Speed Electric Machines
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Solution Overview
Problem
High power density electric machines face thermal management challenges due to heat generation, leading to inefficiencies, component degradation, and potential failure, especially in high-speed operations where conventional cooling methods fail to maintain uniform temperatures and material integrity.
Innovation Solution
A direct cooling system is implemented within the airgap of electric machines using a new cooling circuit routed through interdigitated armature laminations, with cooling manifolds and axial holes delivering cooling fluid to the rotor assembly, effectively managing thermal energy and reducing temperature non-uniformities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high power density electric machines are designed to increase power output, then power delivery is improved, but heat generation increases leading to thermal management failures
Solution Approach 1:
The cooling circuit is nested within the airgap space between rotor and stator, utilizing the existing geometric space. Cooling channels are formed within the rotor assembly structure itself, with distribution passages and discharge passages integrated into the rotor body, allowing cooling fluid to flow through the airgap region without adding external cooling components.
Solution Approach 2:
A cooling fluid is introduced as an intermediary substance to transfer thermal energy from the rotor assembly to the surrounding environment. The cooling fluid flows through distribution passages and discharge passages in the airgap, absorbing heat from the rotor and carrying it away, thereby mediating the thermal management between the heat-generating rotor and the external cooling system.
2Temperature
If conventional cooling methods are used, then cooling is provided, but uniform temperature distribution is not achieved leading to material degradation
Solution Approach 1:
The cooling system provides localized cooling to different regions of the rotor assembly through multiple distribution passages and discharge passages positioned at different locations. This ensures that heat is removed from critical areas where it is generated, maintaining uniform temperature distribution across the rotor and preventing localized thermal hotspots that could cause material degradation.
3Productivity
If high speed operations are performed, then productivity is improved, but thermal energy build-up increases causing temperature non-uniformities
Solution Approach 1:
The cooling fluid flows continuously through the distribution passages and discharge passages in the airgap, providing continuous heat removal during high-speed operation. This continuous cooling action counteracts the thermal energy build-up that occurs during high-speed operation, maintaining temperature uniformity and enabling sustained high-speed operation without thermal degradation.
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 enhances cooling efficiency, allows for higher speed operations, and maintains uniform temperatures across the rotor system, preventing material integrity issues and improving the overall performance and reliability of high power density electric machines.
Implementation Method 1
a cooling fluid supply for selectively directing a cooling fluid into the airgap
Implementation Method 2
heat is typically generated in an electric machine through electric resistance in electric current flowing through a rotor and/or stator
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
An airgap cooling system (140) for an electric machine (100), the electric machine (100) including a rotor assembly (102) rotatably mounted within a stator assembly (120) and defining an airgap (130) therebetween, wherein the stator assembly (120) comprises a lamination stack (124). The airgap cooling system (140) includes a plurality of distribution passages (142) that extend through the lamination stack (124); a plurality of discharge passages (150) that extend between the plurality of distribution passages (142) and the airgap (130); a cooling manifold (160) defining an annular distribution plenum (164) in fluid communication with the plurality of distribution passages (142) , wherein the cooling manifold (160) is configured for receiving a cooling fluid (144) and directing the cooling fluid (144) into the distribution plenum (164), through the distribution passage (142) and the discharge passage (150), and into the airgap (130).