Three-Legged Wound Core Geometry for Lower Transformer Iron Loss
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Solution Overview
Problem
Existing three-phase three-legged wound transformer cores face high iron loss due to magnetic flux concentration, distortion of magnetic flux waveform, and in-plane eddy-current loss, which are exacerbated by the use of multiple materials with different magnetic properties, complicating design and reducing productivity.
Innovation Solution
A three-phase three-legged wound core design featuring two adjacent inner cores and one outer core, with specific magnetic flux density and bent portions, and a grain-oriented electrical steel sheet with controlled magnetic properties, reduces magnetic flux concentration and distortion, using a single material type to achieve low transformer iron loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If multiple materials with different magnetic properties are used to reduce magnetic flux concentration, then transformer iron loss is reduced, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent introduces bent portions at specific corner sections of the core to locally alter magnetic flux distribution. This localized structural modification addresses magnetic flux concentration problems without requiring multiple materials with different magnetic properties, thereby reducing design complexity while maintaining energy loss reduction benefits
Solution Approach 2:
The patent changes the geometric parameters of the core by introducing bent portions with specific angles (55° or less) at corner sections. This parameter change modifies the magnetic path length distribution and flux density distribution, reducing magnetic flux concentration and iron loss without complicating the material selection and design process
2Loss of energy
If bent portions with small angles are introduced to reduce magnetic flux concentration, then transformer iron loss is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The bent portions are introduced during the core manufacturing process itself, allowing the angle precision to be controlled at the fabrication stage. This preliminary action ensures that the angle precision requirement is met during production, and the benefit of reduced iron loss is achieved without requiring additional post-manufacturing adjustments
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
The design achieves low transformer iron loss and excellent magnetic properties without requiring multiple materials, simplifying design and enhancing productivity.
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
Grain-oriented electrical steel sheets with a crystal structure in which <100>, an axis of easy magnetization of iron, is highly aligned in the rolling direction of the steel sheet
Implementation Method 3
the occurrence of magnetic flux concentration at an inner core due to the difference in magnetic path length; the local distortion of magnetic flux waveform in an iron core stemming from three-phase excitation
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 55° or less; and the grain-oriented electrical steel sheet has a magnetic flux density B8 of 1.92 T or more and 1.98 T or less at a magnetic field strength H of 800 A/m.