Conductor Insulation Arrangement for Electric Machine Thermal Management
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Solution Overview
Problem
Existing insulation systems for segmented conductors in electric machines, particularly in hybrid-electric vehicles, face a trade-off between providing high integrity electrical insulation and maintaining thermal performance, as additional insulation bands can block cooling fluid and degrade thermal efficiency.
Innovation Solution
A dual insulation system comprising a resin-based enamel coating and friction-fit or spiral-wrapped insulation sleeves that cover the U-turn and in-slot portions of conductors, leaving tip portions uncovered to allow air passages for cooling, thereby enhancing thermal performance without the need for thick insulation bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If insulation bands are added on conductor ends, then electrical insulation integrity is improved, but thermal performance deteriorates due to blocked cooling fluid passage
Solution Approach 1:
The insulation system is segmented into two distinct parts: enamel coating applied directly to the conductor surface and separate insulation sleeves positioned at critical locations (U-turn portions and connection ends). This segmentation allows the enamel to provide continuous base insulation while the sleeves provide additional protection only where needed, without blocking cooling passages.
Solution Approach 2:
Additional insulation is applied locally only at specific critical regions (U-turn portions and connection ends) rather than uniformly along the entire conductor. The insulation sleeves are positioned precisely at these locations to provide enhanced protection where electrical stress is highest, while leaving the cooling fluid passages clear for optimal thermal management.
2Reliability
If thick insulation bands are used to protect against thermal damage from welding, then electrical insulation is improved, but cooling fluid flow is blocked and thermal efficiency decreases
Solution Approach 1:
The patent employs thin film insulation sleeves that provide adequate electrical protection without the thickness required by traditional insulation bands. These flexible thin film sleeves conform to the conductor geometry and provide sufficient insulation against welding thermal damage while maintaining clear cooling fluid passages.
Solution Approach 2:
Instead of applying full-thickness insulation along the entire conductor length, the patent applies insulation sleeves of appropriate thickness only at the specific locations requiring enhanced protection (U-turn portions and connection ends). This partial application provides sufficient protection against welding damage without excessively blocking cooling passages.
Data Source
AI summary
An electric machine includes a core with a plurality of slots. Electric conductors are positioned within the slots with connection ends extending from the in-slot portions. A plurality of insulation sleeves separate the plurality of electric conductors. Each insulation sleeve substantially covers one entire conductor, including the in-slot portions and the connection ends of the conductor. A tip portion on each connection end remains uncovered by the insulation sleeve and is electrically connected to another tip portion on another conductor. Air passages are formed between the plurality of insulation sleeves at the in-slot portions and at the connection ends of the plurality of electric conductors.