Segmented Stator Slots for Lower-Loss Electric Motor Windings

Solution Overview

Problem

Electric motors face limitations in power density and efficiency due to thermal and high-frequency losses, particularly when using rectangular wires, as the slot-fill ratio is restricted by thermal limits and the proximity effect, leading to increased current density and losses near the slot opening.

Innovation Solution

The implementation of a stator assembly with segmented slots, featuring sections of different widths, allows for the arrangement of wires with varying gauges, where higher gauge wires are closer to the slot opening and lower gauge wires are further in, reducing direct current resistance and thermal resistance, and increasing the cross-sectional area for improved efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If rectangular wires are used to increase slot-fill ratio, then filling factor is enhanced, but thermal limits and efficiency are restricted due to current density increase near slot opening

Engineering Contradiction:

Improveslot-fill ratioVSAvoidelectrical losses

Core Design Contradiction:

Quantity of substanceVSLoss of energy

Solution Approach 1:

The slot is divided into multiple sections with different widths along its length. The first section (near slot opening) has a smaller width, while the second section (deeper in the slot) has a larger width. This segmentation allows different wire gauges to be placed in different sections, optimizing both filling factor and electrical performance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different sections of the slot are assigned different widths to accommodate different wire types. The first section uses smaller width suitable for higher gauge wires to reduce proximity effect, while the second section uses larger width for lower gauge wires to maximize filling factor. This local differentiation optimizes electrical losses throughout the slot.

Inventive Principle:

Principle #3Local quality

2Power

If higher slot-fill ratio is achieved, then power density increases, but thermal management becomes more difficult due to reduced heat extraction

Engineering Contradiction:

Improvepower densityVSAvoidthermal management

Core Design Contradiction:

PowerVSTemperature

Solution Approach 1:

The slot is divided into multiple sections with different widths along its length. The first section (near slot opening) has a smaller width, while the second section (deeper in the slot) has a larger width. This segmentation allows different wire gauges to be placed in different sections, optimizing both filling factor and electrical performance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different sections of the slot are assigned different widths to accommodate different wire types. The first section uses smaller width suitable for higher gauge wires to reduce proximity effect, while the second section uses larger width for lower gauge wires to maximize filling factor. This local differentiation optimizes electrical losses throughout the slot.

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If single wire size is used in slots, then manufacturing is simplified, but performance is limited due to thermal and efficiency constraints

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidelectrical performance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The slot is divided into multiple sections with different widths along its length. The first section (near slot opening) has a smaller width, while the second section (deeper in the slot) has a larger width. This segmentation allows different wire gauges to be placed in different sections, optimizing both filling factor and electrical performance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different sections of the slot are assigned different widths to accommodate different wire types. The first section uses smaller width suitable for higher gauge wires to reduce proximity effect, while the second section uses larger width for lower gauge wires to maximize filling factor. This local differentiation optimizes electrical losses throughout the slot.

Inventive Principle:

Principle #3Local quality

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 configuration enhances power density and reduces electrical losses by optimizing wire placement, improving heat extraction and motor performance while maintaining efficient thermal management.

Implementation Method 1

As speeds increased, skin effect may cause the current density to increase a surface of the conductors

Methodology Applied

Scientific EffectSkin effect: Skin Effect

Implementation Method 2

proximity effect generates more loss for the conductors closer to a slot opening

Methodology Applied

Scientific EffectProximity effect:

Implementation Method 3

heat extraction of the windings may be enhanced, which may improve an electrical performance of the electric motor

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS12176755B2Systems for electric motor

Publication Date: 2024.12.24 DANA TM4 INC

AI summary

Systems are provided for an electric motor. In one example, a system may include a plurality of segmented slots positioned around an inner surface of a stator, wherein each of the plurality of segmented slots comprises a first section comprising a first width and a second section comprising a second width, the second width different than the first.