Stator Insulation Surface Structure for Creepage Distance
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Solution Overview
Problem
High voltage class electromechanical transducers require increased creepage distance to prevent short circuits, leading to longer end winding portions and increased resistive losses, which reduce performance and necessitate more conductor material, making them less efficient and spatially less compact.
Innovation Solution
The stator assembly incorporates elevated surface portions on the outer insulation to increase creepage length without extending the insulation, thereby reducing the amperage of unwanted creepage currents and allowing for shorter end windings, improved efficiency, and reduced material usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the insulation device is extended to increase creepage distance for higher voltage classes, then electrical insulation reliability is improved, but the end winding portion length increases leading to higher resistive losses
Solution Approach 1:
The outer surface of the outer insulation portion is transformed from a flat two-dimensional surface to a three-dimensional surface with elevated portions. This dimensional change increases the creepage distance along the surface without extending the axial length of the insulation device, thereby reducing end winding length and resistive losses while maintaining insulation reliability
Solution Approach 2:
Elevated surface portions are introduced on the outer insulation surface, creating a curved or raised topography. This curvature increases the creepage path length between conductive parts and the frame structure, achieving higher voltage class insulation requirements without increasing the overall insulation device length
2Reliability
If the end winding portion length is increased to achieve necessary creepage distance, then electrical insulation is improved, but the transducer performance decreases due to higher resistive losses
Solution Approach 1:
By utilizing the radial and circumferential dimensions of the insulation surface through elevated portions, the creepage distance is increased without extending the axial dimension. This allows sufficient creepage distance for electrical insulation while keeping the end winding portion short, thereby maintaining high transducer performance
3Reliability
If the insulation device length is extended to prevent short circuits in high voltage applications, then electrical safety is improved, but the transducer becomes less spatially compact
Solution Approach 1:
The insulation device utilizes the surface topology of the end winding portion by introducing elevated portions on its outer surface. This approach increases the creepage distance along the curved surface while maintaining a compact axial profile, achieving electrical safety without increasing the transducer's spatial dimensions
Data Source
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AI summary
It is described a stator assembly (110) comprising (a) a frame structure (212) having a plurality of stator teeth (212a) being circumferentially distributed around a longitudinal axis (190a), wherein in between respective two neighboring stator teeth (212a) there is formed one stator slot (212b); (b) a winding system having a plurality of electric windings (214, 314, 414), wherein respectively one electric winding is wound around at least one stator tooth and is partially accommodated within two stator slots and each electric winding comprises an end winding portion (314a, 414a) which axially protrudes from the frame structure (212); and (c) an insulation arrangement having a plurality of electric insulation devices (530, 830), each insulation device surrounding a part of one electric winding. Each insulation device comprises (c1) an inner insulation portion (532, 832) being accommodated within the respective stator slot and an outer insulation portion (534, 834) protruding from the frame structure (212) and surrounding a part of the respective end winding portion (314a). The outer insulation portion comprises an outer surface which comprises elevated surface portions (536, 836) .