Transformer Core Segmentation for Fine Voltage Control
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Solution Overview
Problem
Transformers used in wind turbines face challenges in voltage regulation due to high voltage stress and limited control precision on the low-voltage side, making it difficult to achieve fine voltage adjustments with existing tap changers.
Innovation Solution
The transformer core is designed with a breakthrough in the cross-sectional plane, allowing only part of the core leg or yoke to encompass the flux, reducing the induced voltage and enabling finer voltage gradation by guiding turns through the gap, and using a ribbon conductor with insulation for secure electrical isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a tap changer is arranged on the high-voltage side to enable voltage regulation, then voltage control capability is improved, but the device complexity and manufacturing difficulty increase due to high voltage stress
Solution Approach 1:
The patent inverts the conventional approach by placing the tap changer on the low-voltage side instead of the high-voltage side. This inversion reduces the voltage stress on the tap changer components, simplifying manufacturing while maintaining voltage control capability. The low-voltage tap changer can be constructed with simpler insulation requirements and lower dielectric strength needs.
Solution Approach 2:
The patent segments the winding into multiple sections with different numbers of turns, allowing the tap changer to select between different combinations of these segments. This segmentation enables fine voltage regulation by switching between partial windings rather than requiring a single large winding with many taps.
2Power
If the low-voltage winding uses strip conductor with complete axial length to handle high nominal currents, then current carrying capacity is improved, but the number of turns is limited reducing voltage regulation precision
Solution Approach 1:
The strip conductor winding is segmented into multiple sections along the axial direction, with each section having a different number of turns. This segmentation allows the tap changer to select between different effective turn combinations, achieving fine voltage regulation while maintaining the high current carrying capacity of the strip conductor structure.
Solution Approach 2:
The patent introduces axial segmentation as an additional dimension for voltage control, complementing the traditional radial winding structure. By varying the axial extent of the active winding section, the effective number of turns can be adjusted continuously, providing fine voltage regulation capability without compromising the current carrying capacity.
3Loss of energy
If the transformer core uses complete cross section for flux enclosure to maximize magnetic coupling, then transformation efficiency is improved, but the induced voltage per turn is too high for fine voltage control
Solution Approach 1:
The core cross-section is segmented into multiple regions, with each region corresponding to a different winding section. By activating different combinations of these core regions through the tap changer, the effective magnetic path area is varied, which adjusts the induced voltage per turn and enables fine voltage control while maintaining efficient magnetic coupling in the active regions.
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 design allows for more precise voltage control on the low-voltage side with reduced manufacturing complexity and increased controllability, enabling +/- 15% adjustments in smaller steps, enhancing adaptability to varying wind conditions.
Implementation Method 1
The induced voltage per closed conductor loop depends on the network frequency, flux density and core cross section
Data Source
Figure 1~2
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AI summary
The invention relates to a transformer comprising a transformer core (50, 70) with at least one core leg (10, 30, 64, 78, 80, 102 + 104) and a main winding (106a,b, 112) arranged around the respective core leg (10, 30, 64, 78, 80, 102 + 104) in a hollow cylinder-like winding area (62) and an auxiliary winding (108a,b, 114) electrically connected thereto and arranged close to the core. The cross-section of the core leg (10, 30, 64, 78, 80, 102 + 104) and/or of a formed core yoke of the transformer core (50, 70) has at least two areas (12, 14, 32, 34) separated by a hole in a cross-sectional plane implied perpendicular to their respective extension, and at least one turn (18, 20, 38, 40, 84, 86) of the respective auxiliary winding (108a,b, 114) is led through the hole.