AC Machine Stator Winding Layout for Lower Torque Ripple
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Solution Overview
Problem
Existing design methods for alternating current machines, such as permanent magnet synchronous machines and induction machines, struggle to optimize stator slot structures independently of designer preferences, leading to suboptimal performance in terms of torque ripple and average torque.
Innovation Solution
A design method that approximates the winding placement in the stator slots using a pulse function based on a sinusoidal function with a superimposed third harmonic, followed by expanding cross-sectional areas of windings and combining adjacent windings to form winding assemblages, determining slot placements to achieve a unique and optimal stator structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional sizing optimization methods starting from a basic structural model are used, then the design process is simple and easy to implement, but the performance improvement is limited and cannot achieve significant reduction of torque ripple and increase of average torque
Solution Approach 1:
The patent segments the stator slot structure into multiple discrete parameters (slot width, slot depth, winding placement positions, etc.) and optimizes each parameter independently through systematic calculation rather than treating the structure as a unified basic model. This segmentation enables precise control over electromagnetic field distribution, reducing torque ripple while maintaining design efficiency.
Solution Approach 2:
The patent systematically changes multiple structural parameters simultaneously, including slot dimensions, winding placement positions, and phase distribution patterns. By calculating optimal values for each parameter based on electromagnetic principles rather than relying on basic model adjustments, the method achieves significant performance improvement in torque characteristics while maintaining a structured design approach.
2Adaptability or versatility
If different designers use their own judgment to determine optimal stator slot structures, then design flexibility is maintained, but the results vary among designers and cannot achieve unique determination of optimal structure
Solution Approach 1:
The patent creates a self-determining design system where the optimal stator slot structure is calculated automatically through systematic formulas and electromagnetic principles. The method eliminates designer subjectivity by using objective calculations based on machine specifications, electromagnetic requirements, and optimized parameter relationships, ensuring unique determination of optimal structure regardless of which designer performs the calculation.
Solution Approach 2:
The patent establishes fixed relationships and calculation methods for determining slot structure parameters based on electromagnetic principles and performance requirements. By defining systematic procedures for calculating slot width, depth, winding placement, and phase distribution, the method ensures consistent results across different designers while maintaining the flexibility to adapt to various machine specifications.
3Ease of manufacture
If conventional winding placement methods are used, then the manufacturing process is simple, but the torque ripple cannot be reduced and average torque cannot be increased
Solution Approach 1:
The patent applies local quality optimization by precisely controlling winding placement within specific slot regions and adjusting phase distribution patterns locally. By optimizing the spatial arrangement of windings in different areas of the stator slot and controlling current distribution patterns, the method reduces torque ripple and increases average torque while maintaining manufacturing simplicity through standardized winding configurations.
Solution Approach 2:
The patent utilizes periodic action principles by establishing regular patterns in winding placement and phase distribution that repeat throughout the stator structure. By creating periodic electromagnetic field distributions through systematic winding arrangements, the method achieves improved torque characteristics while maintaining manufacturing simplicity through repetitive, standardized patterns.
Data Source
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AI summary
An alternating current machine includes: a rotor (22); a stator (20) having a plurality of slots (21) placed opposite the rotor (22) in a circumference direction of the stator (20); and windings of a plurality of phases wound in the plurality of slots (21). A total number of windings of a first phase, which is any one of the plurality of phases, stored in each of the plurality of slots (21) periodically varies in the circumference direction. A distribution of the total number of windings of the first phase for each period is approximated by Fourier series that uses a fundamental component and a third harmonics component as primary components. A fitted curve of the distribution has a shape obtained by superimposing the third harmonic on a positive half period of a fundamental sinusoidal function, in a phase relationship such that a value of the sinusoidal function is enhanced around a peak value and is canceled around a zero-value.