Porous Separator for Stator End Winding Cooling
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Solution Overview
Problem
Existing methods for insulating end windings in electrical machines face challenges such as inconsistent air flow, potential damage to outer insulation layers, and reduced cooling efficiency due to the use of insulating sheets or increased enamel coating thickness, which can lead to inefficiency and machine failure.
Innovation Solution
A separator with a planar portion and a curved portion, featuring ribs and air holes, is designed to provide electrical separation and air flow between end windings, ensuring secure placement and consistent cooling while preventing wire slippage and drooping, using a resiliently deformable material like high-density plastic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If insulating paper is placed between adjacent groups of windings, then electrical insulation is improved, but air flow through the windings is restricted and cooling efficiency is reduced
Solution Approach 1:
The separator is designed with a porous structure containing multiple air channels that extend through its thickness. These channels allow air to flow through the separator and reach the windings for cooling, while the separator material itself provides electrical insulation between adjacent phase windings. This resolves the contradiction by making the insulating structure itself permeable to cooling air.
Solution Approach 2:
The separator is divided into multiple sections with air channels segmented throughout its structure. The planar portion contains air channels that allow radial air flow, while the curved portion provides additional insulation coverage. This segmentation allows air flow paths to be integrated within the insulating structure rather than blocking it with solid insulating material.
2Reliability
If the thickness of the enamel coating on the wires is increased, then electrical insulation is improved, but the amount of copper for a given size of machine is reduced, and power rating is reduced
Solution Approach 1:
A separate insulating separator is introduced as an intermediary component between adjacent phase windings. This separator provides the necessary electrical insulation without requiring increased enamel thickness on the wires themselves. The separator acts as a dedicated insulating element that preserves copper content while ensuring adequate electrical isolation between phases.
3Reliability
If insulating sheets are inserted between end turns, then electrical insulation is improved, but air flow between end turns is restricted
Solution Approach 1:
The separator incorporates air channels directly within its structure, making it a porous insulating material rather than a solid sheet. These channels permit air to pass through the separator and reach the end turns for cooling, while the separator maintains electrical insulation between adjacent phases. This eliminates the need to choose between insulation and cooling air flow.
4Reliability
If phase separators are driven between end coils by force, then electrical insulation is improved, but the outer insulation layer of individual wires may be damaged
Solution Approach 1:
The separator is pre-formed with a curved portion that matches the expected position and shape of the end windings. This allows the separator to be gently placed into position rather than forced between the windings. The pre-formed shape enables the separator to conform to the winding geometry, reducing the risk of damaging the delicate outer insulation layers during installation.
Solution Approach 2:
The separator includes a curved portion that follows the natural curvature of the end windings. This curved geometry allows the separator to be inserted without forcing, as it naturally conforms to the rounded shape of the windings. The curvature reduces mechanical stress on the wire insulation during installation while ensuring proper electrical isolation.
Data Source
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AI summary
A separator (10, 60, 65) is disclosed for electrically separating groups of end windings (52) in the stator (50) of a rotating electrical machine. The separator comprises a planar portion (12, 14, 64) and a curved portion (16, 62, 66). The planar portion comprises a plurality of ribs (18, 20, 72) and a plurality of air holes (22, 78) therebetween. This can allow circumferential and radial air flow to be delivered to inside the windings, thereby cooling the windings more effectively.