Transformer Iron Core Coating Variation to Suppress Building Factor
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Solution Overview
Problem
Existing methods to reduce the building factor in transformers using grain-oriented electrical steel sheets increase production costs and fail to effectively address magnetic flux transfer in the lamination direction, leading to increased iron loss.
Innovation Solution
The iron core design incorporates a lamination structure with a standard deviation of 2 µm to 5 µm in insulating coating thickness and an interval of 1 mm to 20 mm between steel sheet discontinuities to control magnetic flux transfer, using a step lap structure to offset joint portions in the direction of magnetic flux flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If magnetic domain refining technology is applied to reduce iron loss, then iron loss decreases, but production complexity increases
Solution Approach 1:
The patent applies magnetic domain refining treatment before iron core formation to establish the desired magnetic domain structure in advance. This preliminary action ensures low iron loss is achieved in the steel sheets before they are assembled into the iron core, avoiding the need for complex post-assembly treatments and simplifying overall production.
Solution Approach 2:
The patent introduces non-uniformity in magnetic flux locally at specific positions on the steel sheet surface through magnetic domain refining treatment. This localized treatment creates refined magnetic domains in specific regions without requiring uniform treatment across the entire sheet, reducing production complexity while still achieving reduced iron loss.
2Stability of the object's composition
If stress relief annealing is performed after iron core formation, then internal stress is reduced, but magnetic domain refining effect is lost
Solution Approach 1:
The patent performs magnetic domain refining treatment before iron core formation, establishing the refined magnetic domain structure in advance. By completing this treatment prior to core assembly, the structure is locked in before subsequent stress relief annealing, which then only serves to reduce internal stress without affecting the already-established magnetic domain configuration.
3Ease of manufacture
If conventional iron core design is used, then manufacturing is simpler, but magnetic flux transfer in lamination direction increases
Solution Approach 1:
The patent applies magnetic domain refining treatment at specific locations on the steel sheet surface where magnetic flux transfer occurs in the lamination direction. This localized treatment targets the problem areas without requiring changes to the overall iron core design or manufacturing process, maintaining manufacturing simplicity while reducing magnetic flux transfer loss.
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 effectively suppresses magnetic flux transfer in the lamination direction, reducing the building factor and resulting in a transformer with lower core loss.
Implementation Method 1
a standard deviation σ of a thickness of the insulating coating in a region between a steel sheet discontinuity of one of the single layers and a steel sheet discontinuity of another of the single layers adjacent in a lamination direction is 2 μm or more and 5 μm or less
Implementation Method 2
The iron loss of grain-oriented electrical steel sheets is mainly composed of hysteresis loss and eddy current loss
Implementation Method 3
heat loss (iron loss) that occurs when grain-oriented electrical steel sheets are AC magnetized
Data Source
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AI summary
By controlling variation in insulating coating thickness of grain-oriented electrical steel sheets with insulating coating used in an iron core, an increase in building factor caused by magnetic flux transfer in a lamination direction of the iron core is suppressed. An iron core for a transformer including a lamination of a plurality of single layers each including one or more sheets of grain-oriented electrical steel sheet with insulating coating. Each of the single layers has at least one steel sheet discontinuity extending in a direction that intersects with a direction of magnetic flux flow in the single layer. A standard deviation σ of a thickness of the insulating coating in a region between a steel sheet discontinuity of one of the single layers and a steel sheet discontinuity of another of the single layers adjacent in a lamination direction is 2 µm or more and 5 µm or less.