Stator Core Segmentation for Torque Ripple Reduction
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Solution Overview
Problem
The existing stator configurations for AC motors suffer from magnetic saturation in the connecting portions, leading to torque ripple and poor steering feeling in electric vehicles due to undesired magnetic flux distribution.
Innovation Solution
The stator core design includes an annular yoke portion, tooth portions, and slots, where the slots are partitioned by connecting portions into radially-outer and radially-inner sections, allowing currents flowing through the in-slot portions to create opposing magnetic fields, thereby reducing magnetic flux through the connecting portions and preventing saturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an annular connecting portion is used to connect all tooth portions circumferentially, then the assembly process is facilitated, but magnetic saturation occurs in the connecting portion causing torque ripple
Solution Approach 1:
The patent divides the single annular connecting portion into multiple radial connecting portions that connect adjacent tooth portions individually. This segmentation prevents the formation of a continuous circumferential magnetic flux path, thereby avoiding magnetic saturation and torque ripple while maintaining the structural benefit of connecting tooth portions.
Solution Approach 2:
The patent extracts the problematic annular connecting portion that causes circumferential magnetic flux and replaces it with discrete radial connecting portions. This removal of the harmful continuous structure eliminates the magnetic saturation issue while preserving the necessary mechanical connection between tooth portions.
2Adaptability or versatility
If tooth portions are separately formed and assembled to the yoke portion, then manufacturing flexibility is improved, but magnetic flux distribution is disrupted causing saturation in connecting portions
Solution Approach 1:
The patent applies different structural qualities to different regions: the yoke portion and tooth portions are separately formed for manufacturing flexibility, while the connecting portions are specifically designed with radial orientation to ensure proper magnetic flux distribution. This local differentiation resolves both the manufacturing flexibility requirement and the magnetic flux distribution reliability.
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
This design effectively suppresses torque ripple and improves the steering feeling in electric vehicles by ensuring balanced magnetic flux distribution and minimizing magnetic saturation in the connecting portions.
Implementation Method 1
a stator coil mounted on the stator core so as to have a plurality of in-slot portions each of which is received in a corresponding one of the slots of the stator core
Implementation Method 2
when the stator coil is energized so that the direction of current flowing through the in-slot portions received in the radially-outer section is the same as that of current flowing through the in-slot portions received in the radially-inner section, the directions of magnetic fields respectively created by the two currents will be opposite to each other at the corresponding connecting portion. Consequently, it is possible to reduce the resultant magnetic flux flowing through the corresponding connecting portion, thereby preventing the corresponding connecting portion from being magnetically saturated.
Data Source
AI summary
A stator for an electric rotating machine includes a stator core that has an annular yoke portion, a plurality of tooth portions, a plurality of connecting portions and a plurality of slots. The tooth portions are separately formed from and assembled to the yoke portion. Each of the tooth portions extends radially inward from a radially inner periphery of the yoke portion. The tooth portions are arranged in the circumferential direction of the yoke portion at predetermined intervals. Each of the connecting portions circumferentially extends to connect a corresponding circumferentially-adjacent pair of the tooth portions. Each of the slots is formed between a circumferentially-adjacent pair of the tooth portions. Moreover, each of the slots is partitioned by a corresponding one of the connecting portions into a radially-outer section and a radially-inner section.