Phase-Separating Slot Liner for Cooling Dense Motor Windings
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Solution Overview
Problem
Existing rotary electric machines face challenges in balancing the need for compact windings that minimize size and weight with effective cooling and electrical insulation, while also preventing arcing and short circuits, particularly in high-power applications.
Innovation Solution
A flexible, electrically non-conductive slot liner with phase separator arms and surface features that secure windings in place, enhance coolant flow, and accommodate temperature sensors, made from materials like dielectric plastic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If windings are tightly packed in slots to minimize machine size and weight, then the conductive wire utilization is improved, but cooling effectiveness deteriorates due to reduced coolant access and winding surface contact
Solution Approach 1:
The slot liner is segmented into multiple functional zones: a first region with a first thickness for electrical insulation, a second region with a second thickness for cooling, and a third region with a third thickness for mechanical support. This segmentation allows each region to be optimized for its specific function, enabling tight winding packing while maintaining effective cooling through the thicker second region that provides greater coolant flow channels and thermal management capability.
Solution Approach 2:
The invention transitions from a conventional two-dimensional slot liner to a three-dimensional structured component with varying thickness across different regions. The thickness variation creates additional thermal management volume within the slot, allowing coolant to flow through multiple pathways and increase winding surface contact area without increasing the overall slot occupancy, thus resolving the contradiction between compact packing and cooling effectiveness.
2Power
If windings are tightly packed in slots to minimize machine size, then the power density is improved, but the risk of arcing and short circuits between phases increases
Solution Approach 1:
The slot liner exhibits local quality through region-specific thickness optimization. The first region provides enhanced electrical insulation with greater thickness in areas where phase separation is critical, directly addressing the arcing and short circuit risk. This localized insulation enhancement ensures reliable electrical isolation between adjacent phase windings while allowing tight packing in other regions, thereby maintaining high power density without compromising safety.
3Volume of moving object
If conventional thin slot liners are used to fit windings in slots, then the slot space utilization is improved, but cooling effectiveness and winding security deteriorate
Solution Approach 1:
The slot liner incorporates a retention structure with retention arms that can be positioned in different configurations to secure windings dynamically. The retention arms can engage with the winding ends or slot walls to prevent winding displacement during operation, addressing the winding security issue. Simultaneously, the dynamic retention mechanism allows for easy assembly and disassembly, facilitating maintenance while maintaining compact slot utilization.
4Temperature
If slot liners are made thicker to improve cooling, then the cooling channels are enhanced, but the slot space for windings is reduced
Solution Approach 1:
The slot liner is divided into distinct functional regions with different thicknesses optimized for specific purposes. The second region has increased thickness dedicated to cooling functions with integrated coolant flow channels, while the first and third regions maintain appropriate thicknesses for insulation and support. This segmentation enables enhanced cooling capability without proportionally reducing the space available for windings, as each region contributes differently to the overall slot occupancy.
Solution Approach 2:
The thickness enhancement is applied locally only where cooling is most needed, rather than uniformly across the entire slot liner. The second region with improved cooling channels is positioned strategically to maximize thermal management effectiveness, while other regions maintain minimal necessary thickness. This localized thickening provides superior cooling efficiency while minimizing the impact on winding space availability.
Data Source
AI summary
A slot liner for an electric machine is arranged to be located and removably retained in a slot of a machine to secure a winding in the slot. The slot liner includes a flexible electrically non-conductive material defining a body having a first surface to be located against a wall of the slot and an opposing surface configured to receive a winding therearound. The slot liner also includes a phase separator arm extending adjacent but spaced from the opposing surface, where the opposing surface and the phase separator arm define a space therebetween to accommodate a winding when mounted onto the slot liner. In use, the separator arm extends along the slot to separate a winding mounted on the slot liner from another winding secured in the slot by a slot liner on an adjacent tooth.