Stranded Wire Windings for Electric Machine Stator Slot Filling

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Solution Overview

Problem

Existing electrical machines face challenges in increasing power density and ease of production due to limitations in stator slot filling caused by wire enamel and round copper wire configurations, which restrict the degree of filling and manufacturing efficiency.

Innovation Solution

The use of stranded conductors with a larger cross-section than round copper wires, where individual wires are not insulated from each other and are wrapped in a braided insulation layer, allowing for closer packing and direct contact within the stator slots, enhancing the degree of filling and reducing insulation thickness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If solid copper wires with wire enamel are used, then electrical insulation is provided, but the degree of filling of stator slots is reduced

Engineering Contradiction:
Improveelectrical insulationVSAvoiddegree of filling of stator slots
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The conductor is segmented into multiple individual wires within a stranded conductor structure. Each wire is insulated with wire enamel, but the overall insulation is provided by the braided insulation layer surrounding the entire stranded conductor, allowing for more efficient space utilization in the stator slot.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention uses a composite structure combining multiple copper wires with a braided insulation layer. The braided insulation layer provides the primary electrical insulation while the individual wire enamels provide secondary insulation, creating a composite material system that achieves both insulation requirements and high filling density.

Inventive Principle:
Principle #40Composite materials

2Ease of operation

If stranded conductors with small cross-section are used, then flexibility is improved, but the degree of filling of stator slots is lower

Engineering Contradiction:
ImproveflexibilityVSAvoiddegree of filling of stator slots
Core Design Contradiction:
Ease of operationVSQuantity of substance

Solution Approach 1:

The invention changes the cross-sectional parameter of the stranded conductor to be larger than that of traditional round copper wires, specifically designed to be larger than the cross-section of a circle whose diameter is equal to half the inside width of the gap areas. This parameter optimization maintains flexibility while significantly increasing the filling degree of stator slots.

Inventive Principle:
Principle #35Parameter changes

3Power

If the clear width of gap areas is reduced, then electromagnetic performance is improved, but manufacturing difficulty increases

Engineering Contradiction:
Improveelectromagnetic performanceVSAvoidmanufacturing difficulty
Core Design Contradiction:
PowerVSEase of manufacture

Solution Approach 1:

The invention applies different quality requirements to different regions: the gap areas have minimized clear width for optimal electromagnetic performance, while the stator slot body provides sufficient width for winding insertion. The stranded conductor structure adapts to these local requirements by providing flexibility in the gap area while maintaining structural integrity in the slot body.

Inventive Principle:
Principle #3Local quality

4Quantity of substance

If flat wires are used, then degree of filling is improved, but manufacturing time increases

Engineering Contradiction:
Improvedegree of filling of stator slotsVSAvoidmanufacturing time
Core Design Contradiction:
Quantity of substanceVSLoss of time

Solution Approach 1:

The invention uses stranded conductors that are dynamically flexible yet structurally stable. The stranded structure allows the conductor to adapt its shape during insertion into the stator slot, similar to the flexibility advantage of flat wires, but maintains round-cross-section characteristics that enable automated winding processes, reducing manufacturing time.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3955423A1Electric machine with stranded wire windings
Publication Date: 2022.02.16 INNOMOTICS GMBH
  • EP3955423A1 patent drawingFigure 1
  • EP3955423A1 patent drawingFigure 2~3
  • EP3955423A1 patent drawingFigure 4~6

AI summary

An electric machine (1) has a stator core (3) which in turn has stator slots (7) that run parallel to an axis of rotation (6) of the electric machine (1) and are arranged in a circular pattern around the axis of rotation (6). The stator slots (7) are open towards the axis of rotation (6), but have a narrower gap (8) at their end facing the axis of rotation (6) compared to the rest of the stator slot (7), or are open on their side facing away from the axis of rotation (6), but have a narrower gap (8) at their end facing away from the axis of rotation (6) compared to the rest of the stator slot (7). The gaps (8) have a clear width (w) viewed circumferentially around the axis of rotation (6). The windings (9) of a stator winding system are arranged in the stator slots (7). The windings (9) in the stator slots (7) are designed as laid windings.They consist of stranded conductors, each of which in turn has several wires (13). The stranded conductors have a cross-section that is larger than the cross-section of a circle whose diameter (d) is equal to half the clear width (w) of the gap areas (8).