Stator Insulation Using Expanding Resin for Complete Cavity Filling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for impregnating resin in electric motor stators result in incomplete filling of cavities, leading to defects, reduced mechanical fixing, and susceptibility to dust, moisture, and mechanical stress, which compromises the motor's performance and service life due to insufficient resin take-up and inability to introduce additives effectively.
Innovation Solution
A method involving a carrier medium, such as prepreg fibers, loaded with impregnating resin and volume-increasing particles, is used to fill slots in stators, where the resin expands upon heating to fill cavities completely, incorporating additives like mica, aluminum oxide, and boron nitride for enhanced insulation and thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional dip impregnation methods are used, then the manufacturing process is simple and fast, but the cavities in the wire winding are not completely filled, leading to defects and reduced reliability
Solution Approach 1:
The wire winding is pre-impregnated with impregnating resin before being placed in the slot, ensuring that the resin is already distributed within the winding structure. This preliminary action allows the resin to penetrate and fill cavities more effectively during the subsequent curing process, eliminating the need for complex post-impregnation procedures while achieving complete cavity filling and improving reliability.
2Quantity of substance
If the slot is filled to maximum capacity with winding wire and surface insulation, then the slot filling reaches 85% by volume, but at least 15% by volume of free volume remains exposed and cannot be properly filled with impregnating resin
Solution Approach 1:
The impregnating resin is nested within the wire winding structure through pre-impregnation, allowing the resin to be distributed throughout the winding before the winding is placed in the slot. This nested arrangement enables the resin to access and fill internal cavities that would otherwise be inaccessible, achieving complete filling even when the slot is densely packed with winding wire and surface insulation material.
3Reliability
If additives like mica platelets, quartz flour, aluminum oxide, and boron nitride are introduced to enhance thermal conductivity and partial discharge resistance, then the encapsulation properties improve, but the viscosity in the dip bath increases and settling behavior occurs, preventing effective introduction of additives
Solution Approach 1:
Additives such as mica platelets, quartz flour, aluminum oxide, and boron nitride are mixed into the impregnating resin during the pre-impregnation stage, before the resin is applied to the wire winding. This preliminary mixing ensures uniform distribution of additives throughout the resin without requiring them to be introduced through the dip bath, thereby avoiding viscosity increases and settling issues while still achieving enhanced thermal conductivity and partial discharge resistance in the final encapsulation.
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 ensures complete filling of cavities, improves thermal conductivity and partial discharge resistance, reduces mechanical stress on wires, and enhances the motor's performance and service life by eliminating macroscopic pores and defects, while avoiding the limitations of traditional dip impregnation methods.
Implementation Method 1
heating the laminated core at a temperature and speed such that gas-filled particles present in the impregnating resin expand with an increase in volume in such a way that they increase the volume of the not yet cured impregnating resin
Implementation Method 2
Subsequently, the thus impregnated stators are cured over a certain time period through the action of temperature and/or UV irradiation
Data Source
AI summary
Various embodiments of the teachings herein include an electrical insulation system for an electric motor comprising a conductor with wire winding in a slot of a laminated core of a stator. The wire winding is embedded in an encapsulation. The encapsulation includes volume-increasing particles.