Hairpin Winding Stator Assembly for Radial Core Insertion
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Solution Overview
Problem
Current methods for manufacturing stator assemblies of hairpin winding motors face issues such as high defective rates, increased cogging torque and torque ripples, and inadequate fixing force of hairpin coils, leading to performance degradation and noise, vibration, and harshness (NVH) due to non-uniform magnetic flux and coil insertion methods.
Innovation Solution
A stator assembly design featuring hairpin coils continuously connected in a circumferential direction with a support ring surrounding the stator core, where the stator core is inserted radially into the coils, and yokes with specific protrusions and recessions are used to securely fix the coils, optimizing the coil shape and reducing manufacturing costs by 20-40%.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If shoes are formed on end portions of teeth and hairpin coils are inserted in axial direction, then productivity is improved, but welding defects occur and reliability deteriorates
Solution Approach 1:
The hairpin coils are pre-formed with U-shape configuration and insulation structures before insertion into the stator core. This preliminary preparation ensures proper positioning and insulation before the final assembly, preventing welding defects while maintaining high productivity
Solution Approach 2:
An insulation film is introduced as an intermediary between the hairpin coil and the stator core teeth. This film prevents direct contact that would cause welding defects, while still allowing the coil to be securely positioned in the slot
2Ease of manufacture
If hairpin coils are twisted and bent to wind, then coil formation is achieved, but film is thinned or damaged and insulation performance degrades
Solution Approach 1:
The hairpin coils are pre-formed with the complete U-shape configuration and insulation film structure before insertion. This eliminates the need for twisting and bending operations that would damage the film, while still achieving the required coil geometry through precise pre-forming processes
Solution Approach 2:
The coil formation process is changed from post-insertion twisting and bending to pre-insertion forming. By changing the timing and method of coil shaping, the insulation film is protected from thinning and damage while the coil still achieves the required geometric parameters
3Ease of manufacture
If shoes of teeth are removed and hairpin coils are inserted in radial direction, then coil insertion is simplified, but cogging torque and torque ripples increase and NVH performance deteriorates
Solution Approach 1:
The shoes are pre-formed on the teeth before coil insertion, and the hairpin coils are pre-formed with U-shape configuration. This allows radial insertion of coils while maintaining the shoes for NVH control, as both operations can be performed in advance without conflict
4Ease of manufacture
If stator core shape is designed according to hairpin coil shape, then manufacturing is simplified, but magnetic flux becomes non-uniform and performance degrades
Solution Approach 1:
The design approach is changed from shaping the stator core to match the coil shape, to shaping the coil to match the optimal magnetic flux distribution requirements of the stator core. This parameter reversal allows both simplified manufacturing and optimized magnetic performance
Data Source
AI summary
A stator assembly includes hairpin coils continuously connected along a circumferential direction to form a coil winding, a plurality of stator cores disposed along the circumferential direction and configured to fix the hairpin coils, and a support ring configured to surround an outer circumferential surface of the stator core, wherein each of the stator cores is inserted into the hairpin coils forming the coil winding in a radial direction.