Wind Turbine Generator Stator Gaps for Thermal Management
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Solution Overview
Problem
Large wind turbine generators face uneven temperature distribution along their axial extension, leading to higher magnet temperatures, reduced magnetic characteristics, increased current demand, DC winding losses, and unbalanced performance, which results in vibration and fatigue.
Innovation Solution
The geometry and size of stator gaps between axially adjacent segments are varied along the axial direction to enhance airflow and heat dissipation, with smaller angles or widths in hotter sections to balance temperature profiles, and the use of cooling fans to direct airflow through rotor and stator gaps, optimizing aerodynamic drag for efficient cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling air is blown through the stator gaps to dissipate heat, then heat dissipation is improved, but uneven temperature distribution remains because the same airflow passes through all stator gaps regardless of local temperature needs
Solution Approach 1:
The stator gaps are designed with different geometries and sizes at different axial locations to provide localized cooling characteristics. The first stator gap has a different geometry than the second stator gap, allowing each region to receive appropriate cooling intensity based on its specific thermal conditions.
Solution Approach 2:
The geometry and size parameters of the stator gaps are varied along the axial direction of the generator. By changing the gap dimensions, the airflow characteristics and heat dissipation efficiency are optimized for different thermal zones within the generator.
2Power
If higher currents are used to compensate for reduced magnetic characteristics at high temperatures, then torque production is maintained, but DC winding losses increase
Solution Approach 1:
The generator proactively cools the stator regions before excessive temperature rise occurs by directing cooling air through strategically designed stator gaps. This preventive cooling maintains magnetic characteristics and avoids the need for compensatory current increases.
3Ease of manufacture
If uniform stator gap geometry is used throughout the generator, then manufacturing is simplified, but uneven flux loss and magnetic unbalance occur due to varying temperature distribution
Solution Approach 1:
Different stator gap geometries are implemented at different axial locations to account for varying thermal conditions. The first and second stator gaps have distinct characteristics tailored to their respective regions' cooling requirements, optimizing both performance and reliability.
Solution Approach 2:
The stator gap configuration intentionally breaks symmetry by using different geometries at different axial positions. This asymmetric design compensates for the non-uniform temperature distribution and prevents magnetic unbalance.
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 achieves a balanced temperature profile, reducing flux loss, magnetic unbalance, and vibration, thereby enhancing the generator's performance and extending its lifespan by improving heat dissipation and aerodynamic efficiency.
Implementation Method 1
cooling air can blown through the stator gaps
Implementation Method 2
cooling fans cause an air flow through a rotor stator gap and through the stator gaps
Implementation Method 3
the aerodynamic drag in an axial end region of the generator is smaller than the aerodynamic drag in a center region of the generator
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
It is described an electric generator for a wind turbine, which comprises a stator (2), a rotor (3) and a plurality of stator gaps (6) between axially adjacent segments (7) of said stator (2). At least one stator gap (6) is inclined compared to a radial direction of said generator with respect to an axial longitudinal section and said inclinations between the stator gaps (6) and said radial direction of the generator vary in axial direction. Alternatively or in addition, a width (w1, w2) of the stator gaps (6) between axially adjacent segments (7) of said stator (2) vary in axial direction. Moreover, an electric generator arrangement (1) comprising an electric generator and a fan (4) is disclosed.