Distributed Stator Recess Layout for Lower Torque Ripple
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Solution Overview
Problem
Stators with distributed windings experience parasitic forces during operation, leading to undesirable torque ripple, vibrations, and noise due to uniform angular spacings of recesses in the stator core.
Innovation Solution
The stator core is divided into winding zones with non-uniform angular spacings between recesses, allowing for a non-uniform arrangement that reduces parasitic forces and cogging torques, thereby minimizing vibrations and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform angular spacing of recesses is used in the stator core, then manufacturing simplicity is maintained, but torque ripple and parasitic forces increase
Solution Approach 1:
The patent applies asymmetry by introducing non-uniform angular spacing between recesses in the stator core. Specifically, at least one arrangement of recesses has different first and second angular spacings, creating an asymmetric pattern that disrupts the uniformity of parasitic force generation. This asymmetric arrangement reduces torque ripple while maintaining manufacturing feasibility through controlled variations in recess positioning.
Solution Approach 2:
The patent implements local quality by differentiating the angular spacing characteristics of recesses based on their specific positions and associations with winding zones. Different arrangements of recesses can have different spacing patterns (first angular spacing within winding zones, second angular spacing between winding zones), allowing localized optimization of force distribution to minimize parasitic effects while maintaining overall structural integrity.
2Device complexity
If uniform angular spacing of recesses is used in the stator core, then structural simplicity is maintained, but vibrations and operating noise increase
Solution Approach 1:
The patent reduces operating noise by introducing asymmetric angular spacing patterns in the recess arrangements. The non-uniform spacing disrupts the periodicity of parasitic forces that would otherwise generate vibrations and noise at predictable frequencies. This asymmetric configuration spreads out force variations, reducing resonant effects and overall noise levels.
Solution Approach 2:
The patent converts the potentially harmful uniform periodic forces into beneficial aperiodic or irregular force patterns. By deliberately introducing non-uniform angular spacing, the regular parasitic forces that cause noise and vibration are transformed into irregular force distributions that cancel each other out more effectively, turning a harmful uniform pattern into a beneficial non-uniform pattern.
3Object-generated harmful factors
If non-uniform angular spacing of recesses is implemented, then torque ripple is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent segments the stator core into distinct winding zones, with each zone containing specific arrangements of recesses. This segmentation allows the non-uniform spacing to be implemented in a systematic, modular manner. Each arrangement can be designed and manufactured independently with specific first and second angular spacings, making the overall complex pattern more manageable and manufacturable through standardized processes.
Data Source
AI summary
A stator for an electric machine includes a distributed stator winding with N phase windings, P pole pairs, and a stator core having slots in which the stator winding is arranged. The stator core is subdivided into 2·P·N winding zones following each other in the circumferential direction and including axial recesses which form at least one set of recesses following each other. At least two recesses are part of one of the winding zones. Each pair of recesses that adjoin each other in the circumferential direction and are part of the same winding zone has a first angular distance from each other in the circumferential direction. Each pair of recesses which adjoin each other and are part of different winding zones has a second angular distance. In at least one set, the first and angular distance differ such that the set is an irregular set.