Soft-Magnetic Stator Insulation for Torque Density

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Solution Overview

Problem

Existing slot base insulation in electrical machines using insulation paper reduces the slot cross-section, limiting the space for winding wires and magnetic flux, which restricts torque density and increases losses due to the inability to utilize the space for magnetic purposes.

Innovation Solution

A soft-magnetic insulation material is applied to the stator slots, providing both electrical insulation and magnetic conduction, allowing for an increased slot cross-section and reduced stator thickness, enabling more winding turns and efficient magnetic flux penetration without saturation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If insulation paper is used for slot base insulation, then electrical insulation is provided, but the slot cross-section is reduced

Engineering Contradiction:

Improveelectrical insulationVSAvoidslot cross-section

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The patent applies a composite material consisting of insulating varnish combined with soft-magnetic particles to the slot base. This composite provides both electrical insulation through the varnish matrix and magnetic flux conduction through the soft-magnetic particles, eliminating the need for traditional insulation paper while maintaining slot cross-section and enabling magnetic utilization of the insulation layer.

Inventive Principle:

Principle #40Composite materials

2Reliability

If insulation paper is used for slot base insulation, then electrical insulation is provided, but torque density decreases

Engineering Contradiction:

Improveelectrical insulationVSAvoidtorque density

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

The composite material of insulating varnish with soft-magnetic particles provides electrical insulation while the soft-magnetic particles enable magnetic flux penetration through the insulation layer. This allows the full slot cross-section to be utilized for magnetic purposes, increasing the effective copper cross-section and thereby increasing torque density compared to traditional insulation paper.

Inventive Principle:

Principle #40Composite materials

3Reliability

If insulation paper is used for slot base insulation, then electrical insulation is provided, but magnetic flux utilization is reduced

Engineering Contradiction:

Improveelectrical insulationVSAvoidmagnetic flux utilization

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The insulating varnish combined with soft-magnetic particles creates a material that is electrically insulating but magnetically conductive. The soft-magnetic particles provide high magnetic permeability, allowing magnetic flux to penetrate through the insulation layer and be utilized by the stator, whereas traditional insulation paper blocks magnetic flux.

Inventive Principle:

Principle #40Composite materials

4Reliability

If slot cross-section is reduced by insulation paper, then insulation is provided, but winding wire space is limited

Engineering Contradiction:

ImproveinsulationVSAvoidwinding wire space

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The composite insulation material provides the necessary electrical insulation while occupying minimal space due to the thin coating application of the varnish. The soft-magnetic particles are dispersed within the varnish matrix, providing magnetic functionality without adding significant thickness, thus maximizing the available space for winding wires.

Inventive Principle:

Principle #40Composite materials

5Temperature

If stator thickness is reduced for thermal reasons, then heat dissipation is improved, but structural strength may be compromised

Engineering Contradiction:

Improveheat dissipationVSAvoidstator structural strength

Core Design Contradiction:

TemperatureVSStrength

Solution Approach 1:

The soft-magnetic particles in the composite insulation material have high thermal conductivity, creating a thermally conductive path from the slot region where heat is generated to the stator yoke and teeth. This allows for effective heat dissipation even with reduced stator thickness, as the composite insulation layer acts as a thermal conduit rather than a thermal barrier.

Inventive Principle:

Principle #40Composite materials

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

The soft-magnetic insulation material enhances torque density and reduces losses by allowing magnetic flux to flow through the insulation, enabling a thinner stator design and gap-free winding wire attachment, thus improving thermal and magnetic performance.

Implementation Method 1

A soft-magnetic insulation material is applied to the stator slots, providing both electrical insulation and magnetic conduction

Methodology Applied

Scientific EffectMagnetic conduction: Ferromagnetism

Implementation Method 2

The soft-magnetic insulation material enhances torque density and reduces losses by allowing magnetic flux to flow through the insulation

Methodology Applied

Scientific EffectSoft-magnetic property: Ferromagnetism

Data Source

PatentUS11611257B2Method and stator for optimized slot base insulation

Publication Date: 2023.03.21 DR ING H C F PORSCHE AG

AI summary

A method is provided for producing a slot base insulation in a stator (210, 220), wherein the stator (210, 220) is part of an electrical machine and is constructed from a ferromagnetic material. The stator (210, 220) is provided with at least one slot (204) to fit a winding wire (122) in the at least one slot (204). The at least one slot (204) is coated with a soft-magnetic insulation material. A stator (210, 220) also is provided with the slot base insulation.