Transformer Iron Core Structure for Magnetostrictive Vibration Suppression
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Solution Overview
Problem
Conventional techniques for reducing transformer noise through magnetostrictive vibration suppression in iron cores are either complex, increase core size, require accurate management of steel sheets, involve time-consuming adhesion processes, or result in low noise suppression due to increased magnetostrictive waveform strain.
Innovation Solution
Creating grain-oriented electrical steel sheets with regions differing in magnetostrictive properties by forming closure domains and non-closure domains, which interfere with each other to suppress overall magnetostrictive vibration and reduce transformer noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a resin or damping steel sheet is sandwiched between grain-oriented electrical steel sheets, then magnetostrictive vibration is suppressed, but the size of the iron core increases
Solution Approach 1:
The invention introduces regions with different magnetostrictive properties (first regions with lower magnetostriction and second regions with higher magnetostriction) within the grain-oriented electrical steel sheets themselves, rather than adding external damping materials. This local differentiation of material properties allows vibration suppression without increasing overall core size.
Solution Approach 2:
The steel sheet creates a composite structure at the micro level by having multiple regions with different magnetostrictive characteristics within a single material body, achieving the effect of composite materials without physically combining different materials that would increase size.
2Object-generated harmful factors
If two types of steel sheets differing in magnetostriction are stacked, then vibration is suppressed, but the production process becomes complex and productivity decreases
Solution Approach 1:
Instead of stacking different types of steel sheets, the invention creates regions with different magnetostrictive properties within a single type of grain-oriented electrical steel sheet. This eliminates the need for complex sorting and stacking processes while achieving the same vibration suppression effect.
Solution Approach 2:
The invention merges the functions of multiple different steel sheet types into a single steel sheet type with spatially varying properties, simplifying the production process by eliminating the need to handle and stack multiple different materials.
3Object-generated harmful factors
If grain-oriented electrical steel sheets are adhered together, then vibration is suppressed, but the adhesion process requires time and may cause non-uniform stress
Solution Approach 1:
The invention extracts the vibration suppression function from the adhesion process itself and implements it through the internal structure of the steel sheets (regions with different magnetostriction). This eliminates the need for additional adhesion steps and associated time losses.
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 effectively reduces transformer noise by controlling the area ratio and shrinkage difference between closure domain and non-closure domain regions, enhancing noise suppression while maintaining productivity and avoiding core size increases.
Implementation Method 1
Main causes of noise are magnetostriction of grain-oriented electrical steel sheets and resulting vibration of iron cores
Data Source
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AI summary
Vibration of an iron core is reduced to reduce transformer noise. An iron core for a transformer comprises a plurality of grain-oriented electrical steel sheets stacked together, wherein at least one of the plurality of grain-oriented electrical steel sheets: (1) has a region in which closure domains are formed in a direction crossing a rolling direction and a region in which no closure domains are formed; and (2) has an area ratio R of 0.10 % to 30 %, the area ratio R being an area ratio, to the whole grain-oriented electrical steel sheet, of a region in which a shrinkage amount at a maximum displacement point when excited in the rolling direction at a maximum magnetic flux density of 1.7 T and a frequency of 50 Hz is at least 2 × 10-7 less than a shrinkage amount in the region in which no closure domains are formed.