Partially Cured Form Coils for Electric Machine Stators
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Solution Overview
Problem
Existing electric machines face challenges with poor insulation quality in form coils, leading to resin drain-out, air pockets, and inadequate heat dissipation, which result in partial discharge and reduced longevity.
Innovation Solution
The method involves impregnating electrical coils with resin and partially curing them into a gelled state before insertion into the stator, using a vacuum pressure impregnated (VPI) process, allowing for improved resin retention, reduced air pockets, and enhanced mechanical flexibility, followed by a global VPI process for full curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If form coils are impregnated with resin and fully cured before insertion into stator, then insulation quality is improved, but the coils lose flexibility and cannot be inserted into machines with small slot pitches
Solution Approach 1:
The patent applies preliminary action by partially curing the resin in form coils before insertion into the stator. The resin is impregnated into the coil windings and allowed to gel partially, providing initial insulation protection and resin retention, while maintaining enough flexibility for subsequent insertion into tight stator slots. This intermediate state resolves the contradiction between needing insulation quality and maintaining adaptability.
2Reliability
If form coils are impregnated with resin using conventional methods, then insulation is provided, but resin drain-out occurs leading to air pockets and poor insulation finish
Solution Approach 1:
The patent applies preliminary action by partially curing the resin before the coils are installed in the stator. This preliminary partial curing causes the resin to gel and thicken, which prevents resin drain-out that would otherwise occur during handling and installation. The gel state locks the resin in place, eliminating air pockets and ensuring complete insulation coverage, thereby resolving the contradiction between providing insulation and preventing harmful resin drain-out.
3Strength
If form coils are fully cured before installation, then insulation strength is maximized, but excess resin build-up occurs leading to cracking and delamination
Solution Approach 1:
The patent applies preliminary action by partially curing the resin in a controlled manner before final installation. This staged approach allows the resin to set enough to prevent excessive build-up and subsequent cracking, while still achieving full insulation strength after the final curing cycle in the stator. The partial pre-curing controls resin flow and distribution, eliminating the harmful effects of excess build-up while maintaining the benefit of strong insulation.
4Stability of the object's composition
If form coils are stored in fully cured state, then insulation is stable, but they cannot be adjusted for different machine configurations
Solution Approach 1:
The patent applies preliminary action by storing form coils in a partially cured intermediate state rather than fully cured. This intermediate gel state provides sufficient stability to maintain insulation properties and prevent resin drain-out during storage and handling, while retaining enough flexibility to allow adjustment and insertion into different machine configurations. The final full curing occurs after installation, ensuring both stability and adaptability.
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 results in superior insulation quality, reduced resin drain-out, improved heat dissipation, and extended longevity of the electrical coils, suitable for a wider range of machines including those with small slot pitches.
Implementation Method 1
The electrical coil held in the mechanical form is impregnated with resin using a vacuum pressure impregnated (VPI) process
Implementation Method 2
The electrical coil is then partially cured into a gelled state
Implementation Method 3
the electric machine stator with the installed electrical coils are then fully cured to solidify the resin
Data Source
AI summary
A method of fabricating an electric machine stator includes inserting one or more electrical coils into a form and partially curing the one or more electrical coils. The method also includes populating the electric machine stator with the one or more electrical coils and curing the electric machine stator with one or more electrical coils.