Three-Legged Wound Core Bending to Reduce Transformer Iron Loss
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Solution Overview
Problem
Existing three-phase three-legged wound core transformers face challenges in reducing transformer iron loss due to magnetic flux concentration, in-plane eddy-current loss, and strain-induced losses, which are not effectively addressed by using multiple materials with different magnetic properties.
Innovation Solution
The design incorporates a grain-oriented electrical steel sheet with specific magnetic properties and a unique core shape featuring flat sections, lap zones, and bent corner sections to minimize magnetic flux concentration and in-plane eddy-current losses, while using a single material type to simplify transformer design and production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If multiple materials with different magnetic properties are used to address magnetic flux concentration, then transformer iron loss can be reduced, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent applies local quality by creating bent portions at specific corner sections of the core where magnetic flux concentration occurs. The bent portions are strategically positioned at inner corner sections of the first and second inner cores and the outer core, creating localized geometric modifications that address magnetic flux concentration only where needed rather than requiring multiple materials throughout the entire core structure.
Solution Approach 2:
The patent changes the geometric parameter of the core by introducing bent portions with specific angles (30° or more) at corner sections. This parameter change modifies the magnetic flux distribution and reduces concentration effects without requiring material substitution, thereby maintaining structural simplicity while achieving energy loss reduction.
2Loss of energy
If multiple materials with different magnetic properties are used to address in-plane eddy-current loss, then transformer iron loss can be reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent maintains homogeneity by using a single type of electrical steel sheet for the entire core structure. The bent portions are formed by mechanical deformation of the same material rather than introducing different materials with varying magnetic properties, thereby simplifying manufacturing precision requirements while still addressing in-plane eddy-current loss through geometric modification.
3Loss of energy
If complex core shapes with multiple materials are used to address strain-induced losses, then transformer iron loss can be reduced, but productivity decreases
Solution Approach 1:
The patent applies curvature by introducing bent portions at corner sections of the core. These bent portions create smooth transitions in the magnetic flux path, reducing strain-induced losses without requiring complex multi-material assemblies. The curved geometry is achieved through straightforward bending processes that maintain high production efficiency.
Solution Approach 2:
The patent changes the geometric parameter of the core by introducing bent portions with specific angles (30° or more) at corner sections. This parameter change modifies the magnetic flux distribution and reduces concentration effects without requiring material substitution, thereby maintaining structural simplicity while achieving energy loss reduction.
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 results in a three-phase three-legged wound core with excellent magnetic properties and low transformer iron loss, simplifying the design process and improving productivity by eliminating the need for multiple materials with different magnetic properties.
Implementation Method 1
a magnetic domain refining technique has been developed. In this technique, nonuniformity is physically introduced to the surface of a steel sheet and the width of magnetic domains is subdivided to reduce the iron loss
Implementation Method 2
the occurrence of magnetic flux concentration at an inner core due to the difference in magnetic path length, the occurrence of in-plane eddy-current loss when the magnetic flux is transferred between an inner core and an outer core
Data Source
AI summary
A three-phase three-legged wound core is disclosed. The three-phase three-legged wound core includes two adjacent inner cores and one outer core enclosing the two inner cores, the inner cores and the outer core including a grain-oriented electrical steel sheet. In the three-phase three-legged wound core, the two inner cores and the one outer core each have a flat section, a corner section adjacent to the flat section, a lap zone in the flat section, and a bent portion in the corner section; the corner sections of the two inner cores and of the one outer core are each provided with two bent portions, the angle formed by the two bent portions being 30° or more; and the grain-oriented electrical steel sheet has a magnetic flux density B8 of 1.84 T or more and 1.92 T or less at a magnetic field strength H of 800 A/m.