Stator End Turn Protection Using Thin Film Coatings
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Solution Overview
Problem
Existing stator arrangements in electric machines do not effectively protect conductive coils from environmental contaminants and prevent shorting when exposed to the surrounding environment, especially in air-cooled generators.
Innovation Solution
The use of protective barriers, such as annular cups made of waterproof, non-conductive materials like polyphenylene sulphide, secured over the stator end turns, along with a sealant to prevent contamination and shorting, and optionally using axial tubes or necks to enhance sealing and heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the stator is exposed to the surrounding environment for air cooling, then heat dissipation is improved, but the conductive coils become vulnerable to environmental contaminants and shorting
Solution Approach 1:
The patent applies flexible thin film coatings (epoxy, polyurethane, powder coating, PTFE) over the conductive coils and end turns to provide environmental protection. These thin film barriers prevent contaminants from reaching the coils while maintaining flexibility and thermal transfer capabilities, resolving the contradiction between exposure for cooling and protection from contaminants.
Solution Approach 2:
The patent employs composite material systems combining metal stator components with polymer-based protective coatings (epoxy resins, polyurethanes, PTFE). This composite structure provides both the electrical conductivity needed for coil function and the environmental resistance required for reliable operation in harsh conditions, simultaneously achieving heat dissipation and protection.
2Reliability
If protective barriers are added over the end turns, then coil protection is improved, but device complexity increases
Solution Approach 1:
Instead of adding complex mechanical protective structures, the patent applies thin film coatings directly over the existing coil and end turn assembly. This approach provides comprehensive protection without requiring additional components, fasteners, or complex assembly steps, thus improving reliability while minimizing increases in device complexity.
Solution Approach 2:
The protective barrier function is merged with the existing structural components by applying coatings directly onto the end turns and coils. This integration eliminates the need for separate protective housings or enclosures, reducing overall device complexity while maintaining effective protection against environmental contaminants.
3Reliability
If non-conductive material is used for protective barriers, then coil shorting is prevented, but eddy currents may be produced in metal materials
Solution Approach 1:
The patent specifies using non-conductive thin film materials (epoxy, polyurethane, PTFE) for the protective coating. These materials provide electrical insulation that prevents coil shorting while being too thin to generate significant eddy currents, even if applied over metal surfaces, thus resolving the contradiction between preventing shorting and avoiding eddy current losses.
Solution Approach 2:
The patent changes the electrical conductivity parameter of the protective barrier by selecting non-conductive coating materials. This parameter change ensures electrical isolation of the coils to prevent shorting while the thin film geometry minimizes any potential eddy current effects that could occur with metal protective structures.
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 provides effective protection against environmental contaminants and prevents conductive coil shorting, allowing for reliable operation in challenging environments like salt water or foggy conditions without the need for high capital investments in injection molding.
Implementation Method 1
This adhesive both glues the cap into place and reduces thermal resistance from the end turn to the cup
Implementation Method 2
protective barriers are mounted over the end turns and secured to the stator... to block out environmental contaminants and prevent conductive coil shorting
Implementation Method 3
Epoxy, which typically encases the conductive coils, can be used to at least partially secure the protective barriers to the stator
Implementation Method 4
A non-metal material avoids eddy currents produced in the material
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
A stator arrangement particularly suitable for use in an air-cooled generator or other such electric machine includes a stator with an outer stator surface, an opening therein defining an inner stator surface, and longitudinally opposed stator end surfaces. Conductive coils are supported by the stator, and include end turns overlying the longitudinally opposed stator end surfaces. In order to block out environmental contaminants and prevent conductive coil shorting, protective barriers are mounted over the end turns and secured to the stator.