Stator Coil Segment Variable Cross Section

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Solution Overview

Problem

Existing stator designs for rotating electric machines face a trade-off between improving electrical efficiency and reducing the size of the stator, as increasing the cross-sectional area of coil segments to reduce electrical resistance leads to larger coil ends and overall stator size.

Innovation Solution

The design involves coil segments with varying cross-sectional areas, where the coil end segments have a greater or lesser cross-sectional area than the inner segments, and connection portions are widened towards the outer circumference, allowing for reduced electrical resistance and stator size without increasing the stator's width or height.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the cross-sectional area of the coil segment is increased, then electrical resistance is reduced and electrical efficiency is improved, but the size of the coil end and the stator is increased

Engineering Contradiction:
Improveelectrical resistanceVSAvoidstator size
Core Design Contradiction:
Loss of energyVSVolume of stationary object

Solution Approach 1:

The coil segment is designed with a variable cross-sectional area along its length, where the connection portion at the coil end has a different cross-sectional area than the leg portion inserted in the slot. This local variation allows optimization of electrical resistance at the coil end without uniformly increasing the entire coil segment size, thereby addressing the contradiction between reducing electrical resistance and maintaining compact stator dimensions.

Inventive Principle:
Principle #3Local quality

2Use of energy by moving object

If the cross-sectional area of the coil segment is increased, then electrical efficiency is improved, but the height and width of the stator are increased

Engineering Contradiction:
Improveelectrical efficiencyVSAvoidstator dimensions
Core Design Contradiction:
Use of energy by moving objectVSLength of stationary object

Solution Approach 1:

The invention applies local quality by varying the cross-sectional area of the coil segment at specific locations (connection portion vs. leg portion) rather than uniformly increasing the entire coil. This allows improving electrical efficiency at the coil end where current density is highest, without proportionally increasing the overall stator dimensions.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The coil segment's cross-sectional area is varied along its longitudinal dimension, creating a dimensional gradient. The connection portion has a different cross-sectional area than the leg portion, allowing electrical efficiency optimization in one dimension (cross-section at coil end) without uniformly expanding the stator in all dimensions.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Data Source

PatentEP3886297A1Stator of rotating electric machine and method of manufacturing coil segment
Publication Date: 2021.09.29 TOYOTA JIDOSHA KK
  • EP3886297A1 patent drawingFigure 1~2
  • EP3886297A1 patent drawingFigure 3~4
  • EP3886297A1 patent drawingFigure 5

AI summary

A stator core (10) of a stator (50) includes a plurality of teeth (12) around a rotation axis and slots (14) respectively provided between the teeth (12). A coil (60) that is formed by connecting a plurality of coil segments (40, 62) is wound around the teeth (12). At a coil end (64) of the coil (60) protruding from an end surface of the stator core (10) in the rotation axial direction, a widened portion (40a) is provided in the coil segment (40). Therefore, a cross-sectional area of the coil segment (40) at the coil end (64) is different from that on the inner side of the slot (14).