Wind Generator Stator Tooth Deflection Measurement

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Solution Overview

Problem

Wind generator stator teeth experience deflection and deformation due to magnetic interactions, leading to audible noise and reduced service life, and existing methods fail to measure these deflections without interfering with the generator's geometry.

Innovation Solution

A measuring device with a strain gauge, either electrical or optical, is placed in the air gap between the rotor and stator to detect deflections of stator teeth, allowing for direct measurement of electromechanical energy conversion without altering the magnetically active parts, and can be retrofitted into existing generators.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If strain measurement is performed on stator bars to detect stress, then stress detection capability is improved, but the measurement does not directly provide stator tooth deflection information and requires additional processing

Engineering Contradiction:
Improvestress detectionVSAvoiddirect deflection measurement
Core Design Contradiction:
Measurement precisionVSLoss of information

Solution Approach 1:

The patent introduces an auxiliary stator tooth with an integrated strain gauge as an intermediary measurement element. This auxiliary tooth directly experiences the same magnetic forces and deflections as the main stator teeth, providing direct deflection information without requiring stress calculations from stator bar measurements.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If acceleration sensors are arranged on the rotor or generator structure to measure torque, then torque measurement is achieved, but the measurement is indirect and influenced by mechanical vibrations not originating from magnetic forces

Engineering Contradiction:
Improvetorque measurementVSAvoidmechanical vibrations
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the measurement location from the rotor or generator structure to the air gap region by using an auxiliary stator tooth. This separation allows measurement of magnetic force effects directly at the source without including unrelated mechanical vibrations from the rotor or support structure.

Inventive Principle:
Principle #2Taking out (Extraction)

3Measurement precision

If measuring devices are installed to determine stator tooth deflection, then direct deflection measurement is achieved, but the geometry of the generator is interfered with

Engineering Contradiction:
Improvestator tooth deflectionVSAvoidgenerator geometry
Core Design Contradiction:
Measurement precisionVSShape

Solution Approach 1:

The patent segments the measurement function from the main generator structure by using a separate auxiliary stator tooth. This auxiliary tooth is specifically designed for measurement purposes and can be added without altering the geometry of the main stator teeth that are part of the magnetically active area.

Inventive Principle:
Principle #1Segmentation

4Adaptability or versatility

If existing generators are retrofitted with measuring units, then adaptability is improved, but the measuring units must not alter the magnetically active parts

Engineering Contradiction:
Improveretrofit capabilityVSAvoidmagnetically active area
Core Design Contradiction:
Adaptability or versatilityVSShape

Solution Approach 1:

The patent applies local quality by creating a specialized auxiliary stator tooth with measurement integration that is distinct from the main stator teeth. The auxiliary tooth has the specific quality of being instrumented for measurement, while the main stator teeth maintain their original magnetic properties and geometry unchanged.

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 solution allows for precise measurement of stator tooth deflections, enabling noise reduction and improved generator maintenance by determining the service life and homogeneity of the electromagnetic field, while being resistant to non-magnetic vibrations and electromagnetic fields.

Implementation Method 1

A deformation of the stator tooth caused by the magnetic interaction generates a signal representing a strain, which is forwarded by the measuring unit to the measuring device connected to it in terms of signals

Methodology Applied
Scientific EffectStrain gauge measurement: Piezoresistive Effect

Implementation Method 2

Electric current is generated in the stator by the rotation of the magnet wheel relative to the stator, so that the kinetic energy of the wind is converted into electrical energy

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 3

The magnetic interaction occurring between a single stator tooth and the rotor poles moving past results in magnetic forces. The magnetic interaction causes a force on the stator tooth, which leads to a deflection and/or deformation of the stator tooth

Methodology Applied
Scientific EffectMagnetic force: Lorentz Force

Data Source

PatentEP3589915B1Generator and method for operating a generator
Publication Date: 2023.08.09 WOBBEN PROPERTIES GMBH
  • EP3589915B1 patent drawingFigure 1
  • EP3589915B1 patent drawingFigure 2
  • EP3589915B1 patent drawingFigure 3

AI summary

The invention relates to a generator (130), in particular of a wind energy installation (100), for generating electrical power, comprising a rotor (134) and a stator (132) with stator teeth (142, 142a, 142b) and grooves (162) which are arranged in between said teeth and are intended to receive at least one stator winding, wherein a measuring device (160) for determining the deflection of at least one stator tooth (142a) of the stator (132) is provided in conjunction with the generator (130), wherein the measuring device (160) is connected to at least one measuring unit (170) which is in the form of a strain gauge.