Asymmetric Stator Winding Layout for Lower Torque Ripple
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Solution Overview
Problem
Existing rotating electrical machine stators face challenges in efficient slot filling, electromagnetic performance, torque ripple, AC Joule losses, and manufacturing complexity, particularly in reducing the number of parts and minimizing material usage.
Innovation Solution
A stator design with U-shaped electrical conductors having inclined weld portions relative to the stator axis, allowing for consistent spacing and simplified assembly, which reduces the height of coils and minimizes material usage, while facilitating connections and cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If symmetric three-phase windings are used, then the machine operates reliably with balanced currents, but the stator produces harmful magnetic harmonics that generate torque ripple and acoustic noise
Solution Approach 1:
The patent applies asymmetry by using asymmetric windings with different winding factors for positive and negative sequence currents. This deliberate asymmetry in the stator winding configuration allows the machine to operate with unbalanced currents while suppressing harmful magnetic harmonics, particularly the 5th and 7th order harmonics that cause torque ripple and noise
Solution Approach 2:
The patent changes the winding parameters by specifying different winding factors (kp+) for positive sequence and (kp-) for negative sequence currents. This parameter modification enables the asymmetric winding to selectively attenuate specific harmonic components while maintaining reliable operation under unbalanced conditions
2Object-generated harmful factors
If asymmetric windings are used to suppress harmonics, then torque ripple and acoustic noise are reduced, but the machine requires unbalanced currents that complicate control
Solution Approach 1:
The patent modifies the winding parameters to create different winding factors for positive and negative sequence currents. This parameter change enables the system to reduce torque ripple through asymmetric harmonic suppression while the control system manages the unbalanced currents by injecting appropriate compensating currents based on detected asymmetries
3Object-generated harmful factors
If asymmetric windings are used to reduce acoustic noise, then the machine operates more quietly, but the winding structure becomes more complex
Solution Approach 1:
The patent implements asymmetry in the winding structure by configuring different winding factors for positive and negative sequence currents. This asymmetric configuration suppresses acoustic noise generated by magnetic harmonics while maintaining a relatively simple winding structure that can be integrated into conventional stator designs
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design enhances compactness, reduces manufacturing complexity, minimizes material requirements, and improves electromagnetic performance by reducing torque ripple and AC Joule losses, while allowing for easier assembly and better thermal management.
Implementation Method 1
a stator of a rotary electric machine includes asymmetric windings extending along a stator core, the asymmetric windings having different winding factors for positive and negative sequence currents
Data Source
Figure 1
Figure 2~3
Figure 4a
AI summary
Disclosed is a stator (2) comprising a stator body (25) having notches (21) formed between teeth (23), electrical conductors (22) being housed in the notches (21), at least one part of the electrical conductors being in the form of a U-shaped pin, each comprising first (22e) and second (22f) axially extending legs in the first (A) and second (R) notches respectively, at least one of the first (22e) and second (22f) legs of the electrical conductors (22) extending out of the notches via an inclined welding portion, at least one part of the electrical conductors each having a welding portion, innermost with respect to the longitudinal axis of the stator, the innermost welding portions being inclined with the same inclination with respect to the plane perpendicular to the longitudinal axis of the stator.