Coil Head Potting Channels for Compact Electric Machine Cooling
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Solution Overview
Problem
Conventional cooling systems for electrical machines are inefficient, particularly at the coil heads, leading to increased temperature and reduced performance, and require additional components and manufacturing complexity, increasing the machine's size and mass.
Innovation Solution
The use of a hydrophobic coating material to create longitudinal cooling channels at the ends of the electrical machine, eliminating the need for additional cooling tubes and allowing for direct contact between the coating material and the cooling fluid, thereby enhancing heat transfer and reducing the machine's diameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional cooling systems with external jackets are used, then the stator can be cooled, but the machine diameter increases significantly (20-25% increase)
Solution Approach 1:
The cooling channels are nested within the existing stator structure by forming cavities in the potting material that surrounds the coil heads. The cooling fluid flows through these internal cavities, allowing the cooling system to be embedded within the stator itself rather than adding external jackets, thus cooling the stator without increasing the overall machine diameter.
Solution Approach 2:
The invention transitions from radial cooling (through the stator body) to longitudinal cooling (through the coil heads along the axial direction). By forming cooling channels in the potting material at the ends of the stator, the cooling approach changes dimensionally to target the hottest spots directly, improving cooling efficiency without requiring increased radial thickness.
2Temperature
If cooling channels are passed through the jacket, then coil head cooling is improved, but the machine diameter increases and manufacturing complexity increases
Solution Approach 1:
The cooling channels are merged with the potting material structure itself rather than being separate components. The channels are formed directly in the potting material that already surrounds the coil heads, combining the encapsulation function with the cooling function into a single integrated structure, thereby simplifying manufacturing and assembly.
Solution Approach 2:
The invention changes the physical state and properties of the potting material by selecting materials with appropriate thermal conductivity, mechanical strength, and hydrophobic characteristics. This allows the potting material to serve multiple functions: electrical insulation, mechanical support, and thermal management, eliminating the need for separate cooling system components.
3Temperature
If additional cooling tubes are inserted into the coating material, then cooling is improved, but the assembly complexity increases and the coating material experiences increased fatigue
Solution Approach 1:
The invention extracts and eliminates the separate cooling tubes from the system by forming the cooling channels directly in the potting material. This removes the need for inserting and assembling separate tube components, thereby simplifying assembly and eliminating the thermal interface resistance and mechanical stress that tubes would impose on the potting material.
Solution Approach 2:
The potting material serves its own cooling function by having cooling channels formed within it, eliminating the need for separate cooling system components. The material that provides electrical insulation and mechanical support also provides the cooling pathways, allowing the system to cool itself without additional parts or complex assembly procedures.
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 solution effectively cools the coil heads, improves the machine's compactness, and simplifies assembly, while maintaining performance and reducing the risk of thermal stress on the coating material, thus extending its lifespan.
Implementation Method 1
heat exchange occurs radially and indirectly between the active parts (rotor and stator) of the electrical machine and the cooling fluid... heat flux in the coils travels by conduction from the copper of the coils to the stator
Implementation Method 2
heat exchange occurs radially and indirectly between the active parts (rotor and stator) of the electrical machine and the cooling fluid... transferred to the cooling fluid by convection
Implementation Method 3
the coil heads are encapsulated in a hydrophobic coating material... a cooling channel for the circulation of a cooling fluid is delimited at least partially by said coating material
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The present invention relates to an electrical machine (1) comprising a stator (3), a rotor (2), a housing (4), and two end caps (5). The stator comprises a stator body and coils (6), the ends of which form coil heads (7) outside the stator body. According to the invention, the coil heads (7) are encapsulated in a hydrophobic encapsulating material (8). Furthermore, at each end of the electrical machine, a cooling channel (9) is at least partially delimited by the encapsulating material (8).