Stator Winding Hairpin Casting for Axial Overhang Reduction
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Solution Overview
Problem
Current methods for manufacturing conductor windings for multi-phase generators, particularly in aircraft, result in significant axial overhang lengths due to the need for complex bending and brazing, which increase manufacturing time, cost, and complexity, while also limiting the size of conductor wires and affecting electrical efficiency and thermal management.
Innovation Solution
A method involving casting pre-formed conductors with parallel legs and a bridge portion to connect them, allowing for a more efficient and space-effective configuration that reduces electrical resistance and heat losses, eliminating the need for bending and brazing operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional bending and brazing methods are used to connect conductors, then the conductor path can be formed around the stator core, but the axial overhang length increases significantly (up to 35-60% of stator length)
Solution Approach 1:
The conductor is pre-formed into a hairpin shape with predetermined geometry before insertion into the stator core. The bending operations are performed in advance during conductor fabrication rather than during assembly, allowing for precise control of the conductor path and minimization of overhang length.
Solution Approach 2:
The conductor cross-sectional dimensions are optimized by changing the parameters of the bending process. The hairpin conductor is formed with specific radial and circumferential dimensions that allow it to navigate the stator core geometry efficiently, reducing the axial space required for conductor connections.
2Loss of energy
If conductor size is increased to reduce electrical resistance, then electrical efficiency improves, but the slot dimensions must be enlarged which increases stator size
Solution Approach 1:
The conductor is formed with a hairpin geometry that extends in multiple dimensions - radially outward from the stator core and then circumferentially around the end face. This three-dimensional configuration allows the conductor to achieve longer effective lengths for current carrying without requiring proportionally larger slot dimensions, as the conductor utilizes the available radial and circumferential space efficiently.
3Reliability
If air gaps are maintained between conductors for insulation and cooling, then electrical safety and thermal management are ensured, but the space required for conductor connections increases
Solution Approach 1:
The conductor is formed with curved paths that follow the cylindrical geometry of the stator core. The hairpin conductor bends smoothly around the end face in a circumferential direction, allowing air gaps to be maintained between adjacent conductors while following the natural curvature of the stator assembly, thereby minimizing the axial space required for the conductor overhang.
Data Source
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AI summary
A novel method of manufacture and an improved construction of windings of a stator of an electrical machine are provided, which minimise the axial overhang length of the windings at an end of the stator. The invention further enables the conductor cross-section in the overhang region to be greater than when is passes through the core, which can improve overall electrical efficiency and thermal management in the stator. This is enabled by use of casting methods to cast pre-formed conductors outside of the stator core, and then inserting the cast conductors into slots of the stator core.