Stator Winding Crank Shape Reduces Coil End Height
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Solution Overview
Problem
The existing rotary electric machines have a significant issue with the height of stator windings protruding from the stator core, which leads to overhanging and increased radial width of coil ends, limiting the miniaturization and efficiency of the machines.
Innovation Solution
The stator design incorporates a crank-shaped portion on the turned portions of the stator windings with multiple steps and a crank portion, which reduces the radial width and height of the coil ends by optimizing the winding configuration and insulating film thickness, allowing for tighter winding and reduced interference between adjacent slots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If segment conductors are twisted at the center of the turned portion to insert into circumferentially different slots, then the winding can be formed in the slots, but the height of coil ends protruding from the stator core becomes great, causing overhanging
Solution Approach 1:
The turned portion of the segment conductor is divided into multiple sections: a first turned portion for insertion into the first slot, a second turned portion for insertion into the second slot, and a crank-shaped portion connecting them. This segmentation allows each portion to be optimized independently, reducing the overall coil end height while maintaining manufacturability
Solution Approach 2:
The crank-shaped portion introduces a dimensional change by creating a non-linear path between slots. Instead of a simple twist in one plane, the conductor follows a multi-dimensional path with crank portions that extend in different directions, reducing the axial projection height of the coil ends
2Length of stationary object
If the interval between slots and bend angle of segment conductors are increased, then the coil ends can be reduced in height, but the radial width of coil ends increases
Solution Approach 1:
The crank-shaped portion creates an asymmetric configuration where the conductor path differs on each side of the stator core. The first and second crank portions have different orientations and lengths, allowing optimization of coil end height on one side while controlling radial width on the other side
Solution Approach 2:
The crank-shaped portions introduce curved paths instead of straight or simple angular bends. This curvature allows the conductor to navigate between slots more efficiently, reducing the axial height projection while containing the radial width expansion through smooth transitions
3Reliability
If thicker insulating films are applied to prevent short circuits between turned portions and stator core, then insulation reliability improves, but the radial width of coil ends increases
Solution Approach 1:
Insulating films are applied selectively at critical locations where the turned portions approach the stator core, rather than uniformly across the entire conductor surface. This localized insulation approach provides necessary electrical isolation while minimizing the radial width increase
Solution Approach 2:
The insulating film thickness is optimized to provide sufficient insulation only where needed - at the points of closest approach between turned portions and stator core - rather than applying excessive thickness uniformly. This partial action approach balances reliability requirements with dimensional constraints
Data Source
Figure 1(A)~1(B)
Figure 2(A)~2(B)
Figure 3(A)~3(B)
AI summary
The wire 30 forming the stator winding 20 includes the in-slot portions 40 to be disposed in the slots 14 and 15 of the stator core 12 and the turned portions 42 connecting the in-slot portions 40 disposed in the circumferentially different slots 14 and 15. The turned portions 42 formed on axial opposite end sides of the stator core 12. The crank portion 44 which does not twist is formed at substantially the center of the turned portion 42. Steps are formed at sections of the turned portion 42 which protrude outside the stator core 12 from the slots 14 and 15. Further, the turned portion 42 of the wire 30 also has two steps 48 formed between the substantially central crank portion 44 and each of the steps 46 formed at the protruding sections of the turned portion 42.