Transformer Iron Core Slits for Eddy Current Reduction

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Solution Overview

Problem

Current techniques for reducing eddy current loss in transformers have limitations and require further improvement to enhance efficiency.

Innovation Solution

A transformer design featuring an iron core formed by stacking magnetic sheets with slits in the sheets facing the inner peripheral surface of the coil, which reduces eddy current loss by dividing the magnetic flux and improving magnetic flux distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If conventional iron core structures are used without slits, then the structural integrity and magnetic flux continuity are maintained, but eddy current loss increases due to leaked magnetic flux from the coil

Engineering Contradiction:
Improveeddy current lossVSAvoidiron core structure
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The iron core is segmented by forming slits in the magnetic sheets at the inner peripheral surface facing the coil. These slits divide the continuous magnetic path into separate regions, preventing the formation of large eddy current loops and thereby reducing eddy current loss caused by leaked magnetic flux.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Slits are selectively formed only in the magnetic sheets at the inner peripheral surface that faces the coil, rather than throughout the entire iron core. This localized modification addresses the specific problem area where leaked magnetic flux causes eddy current loss, while maintaining the integrity of other parts of the core.

Inventive Principle:
Principle #3Local quality

2Loss of energy

If slits are formed in magnetic sheets to reduce eddy current loss, then energy loss is reduced, but the magnetic flux distribution and flux leakage characteristics change

Engineering Contradiction:
Improveeddy current lossVSAvoidmagnetic flux distribution
Core Design Contradiction:
Loss of energyVSReliability

Solution Approach 1:

Slits are formed only in the magnetic sheets at the inner peripheral surface facing the coil, rather than in all magnetic sheets throughout the entire core. This partial application of the slit structure is sufficient to reduce eddy current loss from leaked flux without excessively disrupting the overall magnetic flux distribution required for transformer operation.

Inventive Principle:
Principle #16Partial or excessive action

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 reduces eddy current loss, leading to improved transformer efficiency, smaller size, and lighter weight by optimizing magnetic flux flow and minimizing energy consumption.

Implementation Method 1

The loss in the transformer includes eddy current loss due to leaked magnetic flux from a coil

Methodology Applied
Scientific EffectEddy current: Eddy Currents

Implementation Method 2

A slit is formed in at least a magnetic sheet which faces an inner peripheral surface of the coil in a stacking direction of the plurality of magnetic sheets

Methodology Applied
Scientific EffectMagnetic flux: Magnetic Field

Data Source

PatentEP2472534B1transformer
Publication Date: 2020.10.07 MITSUBISHI ELECTRIC CORP
  • EP2472534B1 patent drawingFigure 1A~1B
  • EP2472534B1 patent drawingFigure 2A~2B
  • EP2472534B1 patent drawingFigure 3A~3B

AI summary

A transformer (10) includes a leg iron core (14) including a plurality of magnetic sheets stacked in one direction (Z axis direction), and a coil (21) wound around the leg iron core (14). A slit (16) is formed in at least a magnetic sheet which faces an inner peripheral surface of the coil in a stacking direction of the plurality of magnetic sheets, of the plurality of magnetic sheets. Since eddy current is divided by the slit (16), eddy current density can be reduced. By reducing the eddy current density, loss density in an iron core (15) can be reduced. By reducing the loss density in the iron core (15), loss in the transformer (10) can be reduced.