Salient Pole Rotor Magnetic Compensation for Leakage Flux

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Solution Overview

Problem

Existing synchronous electrical machines with salient poles face challenges in reducing magnetic leakage flux, which affects efficiency and size constraints, particularly in applications like maritime and wind power where increasing space or reducing Ampere-turns is not viable.

Innovation Solution

A rotor design with a magnetic compensation source, such as permanent magnets or complementary field windings, is introduced to generate a complementary magnetic flux that compensates for leakage flux, optimizing power output without increasing the rotor's size by minimizing magnetic saturation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the space between two poles is increased to reduce magnetic leakage flux, then the magnetic leakage is reduced, but the volume and weight of the rotating electrical machine are increased

Engineering Contradiction:
Improvemagnetic leakage fluxVSAvoidvolume of the rotating electrical machine
Core Design Contradiction:
Loss of energyVSVolume of stationary object

Solution Approach 1:

A magnetic compensation source is introduced as an intermediary element positioned in the interpole space. This compensation source generates a complementary magnetic flux that actively counteracts the leakage flux between poles, thereby reducing magnetic leakage without requiring increased spacing between poles, thus maintaining compact machine dimensions

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The rotor structure employs composite magnetic circuit design combining main pole bodies with compensation elements (such as permanent magnets or additional windings) in the interpole regions. This composite configuration enables simultaneous achievement of reduced magnetic leakage and maintained compact geometry through synergistic magnetic flux interaction

Inventive Principle:
Principle #40Composite materials

2Loss of energy

If the Ampere-turns are reduced to decrease magnetic leakage, then the magnetic leakage is reduced, but the machine is downgraded and costs significantly increase

Engineering Contradiction:
Improvemagnetic leakage fluxVSAvoidmachine power output
Core Design Contradiction:
Loss of energyVSPower

Solution Approach 1:

The magnetic compensation source acts as an intermediary that reduces leakage flux without requiring reduction of main excitation Ampere-turns. By introducing this compensating magnetic field in the interpole space, the system achieves reduced magnetic leakage while preserving the original power output capability

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention converts the harmful leakage flux phenomenon into a beneficial configuration by introducing compensation sources that generate complementary flux. This transforms the problematic magnetic leakage into a controlled magnetic interaction that actually improves overall machine performance while reducing energy loss

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

3Power

If the main magnetic flux is increased to optimize power, then the power is optimized, but magnetic saturation occurs at the base of the polar bodies

Engineering Contradiction:
Improvepower outputVSAvoidmagnetic saturation
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The invention extracts or removes the problematic magnetic saturation effect by introducing compensation sources in the interpole space. These compensation sources create a magnetic balance that prevents excessive flux concentration at the pole bases, thereby enabling higher power output without reaching saturation limits

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The compensation sources serve as intermediary elements that mediate between the main magnetic flux and the pole structure. By introducing this intermediate magnetic field, the system achieves optimized power transmission while preventing magnetic saturation through flux distribution control

Inventive Principle:
Principle #24Intermediary (Mediator)

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 approach enhances the efficiency and power supply of rotating machines by partially or fully compensating magnetic leaks, meeting current requirements for compactness and efficiency without enlarging the machine.

Implementation Method 1

A rotor of a synchronous electric machine with salient poles, comprising: induction coils forming a source of magnetomotive force; a magnetic compensation source (400) capable of generating a complementary magnetomotive force (fmm) intended to compensate at least partially for the magnetic flux leakage

Methodology Applied
Scientific EffectMagnetic flux compensation: Magnetic Field

Implementation Method 2

induction coils surrounding each polar body formed by a stack of turns

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 3

The rotor of a synchronous electric machine with salient poles according to the invention may also have one or more of the characteristics of dependent claims 2 to 8

Methodology Applied
Scientific EffectPermanent magnetism: Magnetism

Data Source

PatentEP2541735B1Rotor of a multipolar synchronous electric machine with salient poles
Publication Date: 2019.05.08 JEUMONT ELECTRIC
  • EP2541735B1 patent drawingFigure 1~2
  • EP2541735B1 patent drawingFigure 3~5

AI summary

The rotor has multiple salient poles (10), where a magnetomotive force source (3) is distributed on each of the salient poles. The magnetomotive force source generates magnetic flux to encompass an armature of a stator, where a part of the magnetic flux is generated by dispersing the magnetomotive force source between the salient poles of the rotor. The magnetomotive force source is realized by induction coils (3). The magnetic compensation source is mounted between two pole tips at a level of an interpolar space in a detachable manner.