Electric Machine Insulation With Reduced Mica for SiC Converter Stress
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Solution Overview
Problem
The high voltage loads and accelerated electrical aging in electrical rotating machines, particularly traction motors, due to the rapid switching rates of next-generation power converters like SiC-based systems, necessitate improved insulation materials that can withstand higher electrical field strengths and reduce mica content for sustainability and design flexibility.
Innovation Solution
The use of a polymeric blend with siloxane-modified thermoplastics, such as polyetherimide-siloxane copolymers, in combination with amorphous and semi-crystalline thermoplastics, reduces mica content to less than 30% by volume, enhancing insulation resilience and usability at higher electrical field strengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high mica content insulation (45 vol% or more) is used in electrical rotating machines operated with power converters, then the insulation can withstand voltage loads and partial discharges, but the electrical service life is limited due to accelerated aging from rapid switching rates of next-generation power converters like SiC-based systems
Solution Approach 1:
The patent changes the chemical composition parameters of the insulation material by incorporating siloxane-modified thermoplastics with specific glass transition temperatures and thermal conductivity values, replacing traditional high-mica formulations to achieve better compatibility with SiC power converter switching rates
Solution Approach 2:
The patent uses composite insulation materials combining siloxane-modified thermoplastics with fillers such as aluminum oxide or aluminum nitride, creating a multi-phase composite structure that provides both electrical insulation and thermal management properties necessary for withstanding rapid voltage switching
2Adaptability or versatility
If mica content in insulation is reduced for sustainability and design flexibility, then supply chains are secured and delivery routes shortened, but the insulation's ability to withstand high voltage loads and electrical field strengths is compromised
Solution Approach 1:
The patent modifies the insulation material parameters by reducing mica content below 45 vol% and compensating with siloxane-modified thermoplastics that have tailored glass transition temperatures and dielectric properties, maintaining voltage load withstand capability while enabling design flexibility
Solution Approach 2:
The patent replicates the functional properties of traditional high-mica insulation materials by using siloxane-modified thermoplastics that mimic the electrical and thermal characteristics of mica-based insulations, achieving similar performance without relying on natural mica mining
3Volume of moving object
If insulation thickness is reduced for design flexibility and improved heat dissipation, then the electrical machine size is reduced and thermal management is improved, but the insulation's ability to withstand high voltage stresses from rapid switching is compromised
Solution Approach 1:
The patent changes the material parameters by using siloxane-modified thermoplastics with enhanced dielectric strength and optimized thermal conductivity, allowing thinner insulation sections to withstand the same voltage stresses as thicker traditional insulations while improving heat dissipation
Solution Approach 2:
The patent employs composite insulation structures with siloxane-modified thermoplastics combined with high thermal conductivity fillers, creating a multi-functional material that provides both electrical insulation and active thermal management in reduced thickness
4Productivity
If power converters with higher switching rates (SiC-based systems) are used to improve productivity and efficiency, then the electrical machine output is increased, but the voltage peaks and electrical field strengths damage the insulation and accelerate aging
Solution Approach 1:
The patent modifies the insulation material parameters by incorporating siloxane-modified thermoplastics with specific glass transition temperatures above operating temperatures and optimized dielectric breakdown strength, enabling the insulation to withstand the higher frequency voltage switching of SiC power converters
Solution Approach 2:
The patent replicates the protective function of traditional insulation materials against voltage transients by using siloxane-modified thermoplastics that provide similar or superior resistance to electrical field strengths and partial discharges, while being compatible with modern high-speed switching power converters
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 significantly extends the electrical service life of insulation systems and allows for reduced insulation thickness, improved heat dissipation, and design flexibility, while also addressing sustainability concerns by minimizing mica mining from unstable regions.
Implementation Method 1
the polymer blend with siloxane-modified thermoplastic is not only mica-reduced with less than 30 vol%, preferably less than 20 vol% and particularly preferably less than 10 vol% mica in the fully cured insulation
Implementation Method 2
electrical rotating machines that operate according to IEC 60034-18-42 with the occurrence of partial discharges
Implementation Method 3
allows for reduced insulation thickness, improved heat dissipation
Data Source
AI summary
The invention relates to the use of insulation for an electric rotating machine in combination with certain power converters, in particular with IGBT and/or silicon carbide (SiC)-based power converters, such as those used, for example, to drive rail vehicles, as well as an electric rotating machine equipped with such insulation. The electric rotating machines that are the focus here have all previously used insulation with a high mica content, with mica paper contents of 45 vol% or more. In particular, electric rotating machines that are operated according to IEC 60034-18-42 under partial discharge conditions are the subject of this application. The combination proposed here for the first time makes it possible to use insulation for power converters based on IGBT technology or on silicon-based semiconductors with a larger bandgap, such as...SiC and/or GaN-based rotating electrical machines, such as traction motors, are operated to reduce mica or to largely or completely eliminate mica.