Stator Coil Insulation Using Localized Resin Composition for Heat Resistance
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Solution Overview
Problem
Existing rotating electrical machines face challenges in achieving high-temperature electrical insulation due to low heat resistance of the insulation system inside stator coil slots, particularly with general-purpose impregnating resins having limited usable time and cost constraints.
Innovation Solution
The use of a stator coil configuration that incorporates a bifunctional epoxy resin and an acid curing agent for the impregnating resin, combined with a high-heat-resistance slot liner and mica tape containing alicyclic epoxy resin, forming an integral unit with improved heat resistance and adhesion, enhances the insulation system's heat resistance and electrical insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a general-purpose impregnating resin is used to reduce material cost, then the heat resistance of the insulation system deteriorates
Solution Approach 1:
The patent applies different resin compositions to different locations within the slot insulation system. The first resin composition (with polyfunctional epoxy resin having 3 or more epoxy groups) is used in the slot liner and mica tape where high heat resistance is critical, while the second resin composition (with bifunctional epoxy resin) is used as the impregnating resin for cost-effective overall insulation. This local differentiation allows the system to achieve high-temperature electrical insulation where needed while maintaining low material costs overall.
2Temperature
If a polyfunctional epoxy resin with 3 or more epoxy groups is used in the slot liner and mica tape, then the heat resistance is improved, but the material cost increases
Solution Approach 1:
The patent strategically places the expensive polyfunctional epoxy resin (with 3 or more epoxy groups) only in the slot liner and mica tape components where high heat resistance is most critical for electrical insulation. The more economical bifunctional epoxy resin is used for the impregnating resin that covers the entire coil. This localized application of high-performance material minimizes overall material cost while ensuring adequate heat resistance at critical locations.
3Productivity
If the impregnating resin has long usable time, then the manufacturing efficiency is improved, but the curing speed may be reduced
Solution Approach 1:
The patent selects a bifunctional epoxy resin with specific molecular structure parameters that provide a balance between usable time and curing characteristics. The bifunctional resin offers longer usable time compared to polyfunctional resins, allowing for adequate mixing and injection time during manufacturing. The curing process is optimized through the combination of the specific epoxy resin and acid curing agent ratio, ensuring that while the usable time is extended for manufacturing efficiency, the curing speed remains sufficient to achieve complete insulation performance.
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 configuration effectively improves the heat resistance and electrical insulation of the stator coil, allowing for stable high-temperature operation while maintaining low material costs and extending the usable time of the impregnating resin.
Implementation Method 1
the impregnating resin contains a bifunctional epoxy resin and an acid curing agent
Implementation Method 2
the high-heat-resistance components of the slot liner and the mica tape forma liner cured portion and a mica insulating layer portion as an integral unit
Data Source
AI summary
The rotating electrical machine of the present invention includes a stator coil obtained by curing the impregnating resin injected into the whole stator coil unit after an electrically insulated coil unit with a mica tape having been wrapped around a conductor is slotted into stator iron core slots via a slot liner. The high-heat-resistance resin component of the slot liner contains at least an epoxy resin having 3 or more epoxy groups. The high-heat-resistance resin component of the mica tape contains at least an alicyclic epoxy resin. The impregnating resin contains a bifunctional epoxy resin, and an acid curing agent having one acid anhydride skeleton. With the impregnating resin, the high-heat-resistance resin components of the slot liner and the mica tape form a liner cured portion and a mica insulating layer portion as an integral unit of different resin compositions inside the slot.