Flux Screen With Grooves for Generator Stator Cooling
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Solution Overview
Problem
High power turbine generators experience increased losses and temperatures at the stator core ends due to magnetic flux, leading to reduced insulation life and mechanical weakening, with existing flux shields inducing high losses and requiring liquid cooling.
Innovation Solution
A flux screen with a backside featuring channels, grooves, or pits is used to enhance heat transfer without compromising the shielding effect, optimized with grooves oriented to facilitate cooling medium flow and located in high magnetic flux regions, maintaining the shielding effect while improving cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional flux shields are used to shield the stator core from magnetic flux, then the shielding effect is achieved, but high losses are induced in the shield requiring liquid cooling
Solution Approach 1:
The flux screen is designed with a porous structure consisting of multiple parallel screens with spacing between them, creating a porous-like configuration that allows cooling medium flow while maintaining shielding effectiveness. This structure reduces eddy current losses by breaking up continuous flux paths while still blocking harmful magnetic flux penetration into the stator core.
Solution Approach 2:
The invention transitions from a single solid shield to a multi-dimensional array of parallel screens with spacing, adding spatial dimensionality to the shielding structure. This dimensional change allows cooling medium to flow through the shield structure while maintaining shielding effectiveness and reducing losses.
2Temperature
If radial cooling ducts are provided in the stator core ends, then cooling effectiveness is improved, but the core end structure is mechanically weakened
Solution Approach 1:
The flux screen is segmented into multiple parallel screens rather than a single solid structure, allowing cooling medium to flow through the spaces between screens. This segmentation provides cooling pathways without requiring ducts that would weaken the stator core structure, as the screens are positioned in the end winding region rather than the core itself.
Solution Approach 2:
The flux screen acts as an intermediary structure between the end windings and the stator core, providing cooling functionality without directly compromising the core structure. The screens intercept magnetic flux before it reaches the core while allowing cooling medium flow, serving as a mediator that protects the core without requiring structural modifications to the core itself.
3Object-affected harmful factors
If the flux screen is positioned close to the stator core, then shielding effectiveness is improved, but heat transfer to cooling medium is reduced
Solution Approach 1:
The flux screen structure utilizes the spacing dimension between parallel screens to enable cooling medium flow while maintaining shielding effectiveness. The screens are positioned to be effective against magnetic flux while the spacing between them creates thermal pathways for heat transfer to the cooling medium.
Solution Approach 2:
Different regions of the flux screen structure have different properties: the screens themselves provide magnetic shielding close to the stator core, while the spaces between screens provide thermal transfer pathways. This local differentiation of function allows simultaneous achievement of shielding effectiveness and heat transfer efficiency.
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 solution effectively reduces heat generation and temperature in critical regions by enhancing heat transfer without diminishing the shielding effect, allowing for efficient cooling of high-power generators without the need for liquid cooling.
Implementation Method 1
They are conductive members of low magnetic permeability arranged to provide circulating currents which divert stray flux away from the tooth region
Implementation Method 2
These eddy current shields are typically copper plates or loops situated directly in front of the stator teeth. They are conductive members of low magnetic permeability arranged to provide circulating currents which divert stray flux away from the tooth region
Implementation Method 3
The backside is provided with channels and/or grooves and/or pits
Implementation Method 4
enhance heat transfer without compromising the shielding effect
Data Source
AI summary
A flux screen is provided for shielding a generator stator core from the magnetic field generated by end windings of the stator, wherein the flux screen comprises a frontside to be at least indirectly facing the end windings of the generator and a backside to be at least indirectly facing the stator core of the generator, and wherein the backside is provided with channels and/or grooves and/or pits.