Permanent Magnet Rotor Bridges Using Non-Magnetic Additive Materials

Solution Overview

Problem

Conventional permanent magnet (PM) rotors suffer from magnetic flux leakage due to bridge sections, which compromises both structural integrity and efficiency, necessitating a balance between minimizing flux leakage and maintaining structural strength.

Innovation Solution

A rotor design featuring bridges made of different materials than the rotor hub, with additive manufacturing allowing for integral construction and transition regions, embedding magnets without gaps to reduce flux leakage and enhance structural strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If bridge sections are made larger to provide structural strength, then structural integrity is improved, but magnetic flux leakage increases

Engineering Contradiction:

Improvestructural integrityVSAvoidmagnetic flux leakage

Core Design Contradiction:

StrengthVSLoss of energy

Solution Approach 1:

The rotor hub employs different material properties in different regions: magnetic steel with high permeability in the pole portions for flux conduction, and non-magnetic material with low permeability in the bridge sections for flux isolation. This local differentiation allows each region to perform its specific function optimally without compromising the other.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The rotor hub is constructed as a composite structure combining magnetic steel and non-magnetic materials in a single integral component. This composite approach enables the coexistence of regions with contrasting magnetic properties within one structure, allowing bridges to provide mechanical support while minimizing their detrimental magnetic flux leakage effects.

Inventive Principle:

Principle #40Composite materials

2Loss of energy

If bridge sections are made smaller to reduce flux leakage, then magnetic flux leakage is reduced, but structural strength decreases

Engineering Contradiction:

Improvemagnetic flux leakageVSAvoidstructural integrity

Core Design Contradiction:

Loss of energyVSStrength

Solution Approach 1:

The rotor hub employs different material properties in different regions: magnetic steel with high permeability in the pole portions for flux conduction, and non-magnetic material with low permeability in the bridge sections for flux isolation. This local differentiation allows each region to perform its specific function optimally without compromising the other.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The rotor hub is constructed as a composite structure combining magnetic steel and non-magnetic materials in a single integral component. This composite approach enables the coexistence of regions with contrasting magnetic properties within one structure, allowing bridges to provide mechanical support while minimizing their detrimental magnetic flux leakage effects.

Inventive Principle:

Principle #40Composite materials

3Ease of manufacture

If traditional manufacturing methods are used, then manufacturing simplicity is maintained, but flux leakage cannot be minimized

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidmagnetic flux leakage

Core Design Contradiction:

Ease of manufactureVSLoss of energy

Solution Approach 1:

The rotor hub is manufactured as a single integral component using additive manufacturing technology, merging the bridges and pole portions into one unified structure. This eliminates the need for separate manufacturing and assembly steps while enabling the complex internal geometry required to minimize flux leakage.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

Additive manufacturing enables precise control over the geometric parameters of the bridge sections, allowing optimization of their dimensions and shapes to minimize flux leakage while maintaining structural integrity. The manufacturing process parameters can be adjusted to achieve the desired material properties and structural characteristics.

Inventive Principle:

Principle #35Parameter changes

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 design achieves reduced flux leakage and a more compact, lightweight, or high-power PM machine by utilizing materials like Inconel, titanium, or stainless steel for bridges, offering a size and weight advantage over traditional PM machines.

Implementation Method 1

additively manufacturing a rotor including a rotor hub and a plurality of bridges radially outward of the rotor hub, wherein each bridge is of a different material than that of the rotor hub, and wherein the rotor hub and bridges are additively manufactured integral with one another

Methodology Applied

Scientific EffectAdditive manufacturing: 3D Printing

Implementation Method 2

The bridges can be of a material with lower magnetic permeability than that of the rotor hub. The bridges can be of a material including at least one of Inconel, titanium, stainless steel, or nickel.

Methodology Applied

Scientific EffectMagnetic flux leakage reduction: Magnetic Field

Data Source

PatentEP3232537B1Interior permanent magnet rotor hubs

Publication Date: 2021.04.28 HAMILTON SUNDSTRAND CORP

Figure 1
Figure 2

AI summary

A permanent magnet machine (100) includes a rotor (102) including a rotor hub (104) and a plurality of permanent magnets (108) embedded in the rotor (102) in a circumferential pattern. The rotor (102) includes a respective bridge (110) between each circumferentially adjacent pair of the permanent magnets (108). Each bridge (110) is of a different material than that of the rotor hub (104), and the rotor hub (104) and bridges (110) are integral with one another.