Toroidal Switched Reluctance Machine Azimuthal Flux

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Solution Overview

Problem

Conventional switched reluctance machines (SRMs) face inefficiencies due to high leakage flux and weight issues, particularly in circular geometries, as the magnetic flux is closed in radial and axial directions, leading to poor force generation and increased weight with existing configurations.

Innovation Solution

A switched reluctance machine with a toroidal magnetic circuit configuration, featuring windings around iron cores and iron poles with air gaps, allowing for azimuthal magnetic flux closure, reducing the length of the magnetic circuit and minimizing leakage flux, making it suitable for circular applications.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If conventional prismatic or cylindrical configurations with radial and axial magnetic flux closure are used, then the machine structure is simple, but the leakage flux increases and force generation efficiency decreases

Engineering Contradiction:

Improveleakage fluxVSAvoidmagnetic circuit configuration

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent applies a toroidal (doughnut-shaped) magnetic circuit configuration where the magnetic flux follows a curved azimuthal path around a central axis, rather than radial or axial paths. This curved geometry naturally guides the flux through the iron core and poles, minimizing leakage and improving force generation efficiency while maintaining structural simplicity suitable for circular applications.

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Loss of energy

If the length of the magnetic circuit is reduced in prismatic and circular configurations, then the leakage flux is reduced, but the force produced between both sides is significantly reduced

Engineering Contradiction:

Improveleakage fluxVSAvoidforce produced

Core Design Contradiction:

Loss of energyVSForce

Solution Approach 1:

The toroidal configuration with azimuthal flux closure creates an optimized magnetic path where the flux lines follow a curved trajectory around the central axis. This geometry allows the magnetic circuit length to be minimized while maintaining effective force production between the iron core and poles, as the azimuthal direction provides natural flux containment and reduces leakage without compromising the force-generating interaction.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Reliability

If conventional configurations with iron return yoke are used, then the magnetic circuit is closed, but the total weight of the machine increases

Engineering Contradiction:

Improvemagnetic circuit closureVSAvoidtotal weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The toroidal configuration eliminates the need for separate iron return yokes by using the curved azimuthal path itself as the flux-closing structure. The iron core and poles are arranged in a doughnut shape where the flux naturally returns through the curved path, reducing the total amount of iron required and thereby reducing weight while maintaining complete magnetic circuit closure.

Inventive Principle:

Principle #14Spheroidality (Curvature)

4Ease of manufacture

If conventional radial and axial flux closure is used, then the machine can be manufactured with standard geometries, but poor force generation efficiency occurs when iron is saturated

Engineering Contradiction:

Improvestandard geometryVSAvoidforce generation efficiency

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The toroidal configuration with azimuthal flux closure provides a geometry that is well-suited for circular manufacturing processes while optimizing force generation. The curved azimuthal path distributes magnetic flux more evenly through the iron, delaying saturation effects and maintaining high force generation efficiency throughout the operational range, unlike radial configurations where flux concentration leads to early saturation.

Inventive Principle:

Principle #14Spheroidality (Curvature)

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 toroidal configuration enhances specific force production per unit mass and current, improving operational efficiency and compactness, especially in circular geometries like wave energy converters and cylindrical actuators, by optimizing the force-to-power ratio and reducing weight.

Implementation Method 1

at least one winding wound around an iron core corresponding to the at least one winding, configured to act as an active side of the machine

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

Switched Reluctance Machines (SRM) are based on a mobile magnetic circuit formed by iron core windings and iron poles that aim to maximise or minimise the reluctance thereof

Methodology Applied

Scientific EffectMagnetic reluctance: Magnetic Reluctance

Data Source

PatentEP3979475A1Switched reluctance machine

Publication Date: 2022.04.06 WEDGE GLOBAL SL

Figure 1~2
Figure 3A~3B

AI summary

In accordance with the configuration proposed for the magnetic circuit of the machine of the present invention, the amount of iron used for both the passive poles and the windings on the active side is reduced with respect to other conventional distributions. Furthermore, a predominantly azimuthal magnetic flux is created, which guarantees an efficient production of force for any relative position between the active side and the passive side, even for high iron saturation values.