Flat-Wire Stator Short-Pitch Winding for Lower Torque Ripple
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Solution Overview
Problem
Existing flat wire motors with full-pitch winding structures have high harmonic winding factors, leading to significant torque fluctuation, noise, vibration, and harshness (NVH) issues, which degrade motor performance.
Innovation Solution
A stator winding structure with a flat wire short-pitch winding configuration is implemented, where the equivalent coil pitch is less than the pole pitch, allowing for a high fundamental winding factor while effectively reducing the harmonic winding factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If full-pitch winding structure is used, then high copper fill factor and heat dissipation are achieved, but harmonic winding factor increases leading to torque fluctuation and NVH degradation
Solution Approach 1:
The patent changes the winding pitch parameter from full-pitch to short-pitch configuration. Specifically, the equivalent coil pitch is designed to be less than the pole pitch, creating a short-pitch winding structure that reduces the harmonic winding factor while maintaining the benefits of flat wire winding such as high copper fill factor and improved heat dissipation.
2Object-generated harmful factors
If short-pitch winding is adopted to reduce harmonic winding factor, then torque fluctuation decreases, but fundamental winding factor is compromised due to limited configuration options
Solution Approach 1:
The patent utilizes the axial dimension by stacking multiple layers of flat wire conductors (N layers where N is even and ≥4) in the stator slots. This multi-layer configuration allows for flexible arrangement of phase bands across different layers and circumferential positions, enabling optimization of both fundamental and harmonic winding factors simultaneously through three-dimensional spatial arrangement.
Solution Approach 2:
The patent divides each phase winding into multiple phase units that are evenly distributed around the stator core circumference. Each phase unit contains multiple phase bands formed by adjacent layers of flat wire conductors. This segmentation allows independent optimization of each phase unit's contribution to fundamental and harmonic winding factors, achieving overall optimization when assembled.
3Object-generated harmful factors
If N layers of flat wire conductors are disposed in stator slots with adjacent phase bands staggered by one stator slot, then equivalent coil pitch becomes less than pole pitch, but winding structure complexity increases
Solution Approach 1:
The patent employs uniform staggering of adjacent phase bands by one stator slot across all phase units and layers. This homogeneous arrangement pattern simplifies the winding structure by creating a repetitive, regular configuration that is easier to manufacture and analyze, while still achieving the desired short-pitch effect with equivalent coil pitch less than pole pitch.
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 proposed stator winding structure significantly reduces torque fluctuation, improves output performance, and enhances the overall stability and comfort of electric vehicles by minimizing noise and vibration.
Implementation Method 1
a flat wire motor has a high copper fill factor, heat dissipation of a winding of the motor is facilitated, a voltage endurance capability of the winding can be improved
Data Source
AI summary
A stator, a flat wire motor, a powertrain. A plurality of stator slots are evenly provided on an inner wall of the stator core in a circumferential direction, the stator winding includes flat wire conductors inserted in the stator slots. The flat wire conductors are connected to form m phase windings, each phase winding includes a plurality of phase units that are evenly disposed at spacings in the circumferential direction of the stator core, any phase unit of each phase winding includes at least two phase bands, each phase band of any phase unit includes two adjacent layers of flat wire conductors, and adjacent phase bands of any phase unit are staggered by one stator slot. The stator winding is a short-pitch winding, which reduces back electromotive force harmonics and improves performance of the motor.