Transposed Partial-Conductor Layout for Lower AC Resistance

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Solution Overview

Problem

Existing rigid conductors for AC current are limited by the skin effect, which restricts current transmission to the outer layer, necessitating large diameters and inefficient use of cross-sectional area, while existing solutions for flexible conductors are not applicable to rigid conductors.

Innovation Solution

A conductor design with alternating main sections and transposing junctions, featuring partial conductors with varying outer diameters and electrical insulation, which minimizes the skin effect by distributing current across the entire cross-section.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If large-diameter conductors are used to transmit high AC current, then current capacity increases, but the skin effect causes current to flow only in the outer layer, making the inner cross-section unused and increasing device complexity

Engineering Contradiction:
Improvecurrent capacityVSAvoidconductor structure complexity
Core Design Contradiction:
Quantity of substanceVSDevice complexity

Solution Approach 1:

The conductor is divided into multiple independent partial conductors (at least two) that are electrically insulated from each other in the main sections. Each partial conductor carries a portion of the total current, allowing the current to distribute across the entire cross-section of the composite conductor rather than being confined to the outer layer of a single solid conductor. This segmentation eliminates the skin effect limitation while maintaining high current capacity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent employs a nested configuration where partial conductors are arranged concentrically (one inside another) or in other spatial configurations, with each partial conductor electrically insulated from the others. This nested structure allows efficient use of the entire cross-sectional area, as current flows through all nested layers rather than just the outer surface, thereby increasing current capacity without proportionally increasing outer diameter.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Quantity of substance

If transposing junctions are introduced to minimize skin effect, then current distribution improves, but manufacturing complexity and production difficulty increase

Engineering Contradiction:
Improvecurrent distribution efficiencyVSAvoidconductor manufacturing difficulty
Core Design Contradiction:
Quantity of substanceVSEase of manufacture

Solution Approach 1:

The transposing junctions are pre-designed and pre-positioned during the manufacturing process to establish the alternating pattern of partial conductors in main sections. By preparing the transposing junctions in advance with the correct geometry and insulation, the assembly process is simplified, and the final conductor achieves optimal current distribution without requiring complex post-manufacturing adjustments.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The transposing junctions are designed with specific local characteristics (such as tapered transitions or insulating barriers) that enable the partial conductors to exchange positions while maintaining electrical insulation. This localized structural quality at the junction points allows the overall conductor to achieve uniform current distribution across all sections without requiring the entire conductor length to have complex features.

Inventive Principle:
Principle #3Local quality

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 allows for significantly reduced AC resistance and increased current capacity, enabling up to 170% higher operating current without increased ohmic losses, compared to standard conductors.

Implementation Method 1

Due to the skin effect, the AC component of the current tends to flow only in the outer layer of the conductor of the thickness which is referred to as skin depth.

Methodology Applied
Scientific EffectSkin effect: Skin Effect

Implementation Method 2

The operating current transmitted through the conductor is limited by the heat generated by the ohmic losses in the conductor, which is proportional to the electric resistance of the conductor.

Methodology Applied
Scientific EffectElectrical resistance: Electrical Resistance

Implementation Method 3

The AC magnetic flux, generated by the current in the conductor, flowing through the surface area between two wires, one running closer and another one running further from the conductor axis, induces a loop current flowing in the two wires

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP4044200B1Conductor for electric current, method of manufacturing the conductor and use of conductor for conducting electric current with ac component
Publication Date: 2026.04.01 HITACHI ENERGY LTD
  • EP4044200B1 patent drawingFigure 1
  • EP4044200B1 patent drawingFigure 2
  • EP4044200B1 patent drawingFigure 3A~3D

AI summary

A conductor (1, 10) for conducting electric current has along its length (L) at least two main sections (2, 2', 3, 3', 18, 19, 20) comprising at least a first main section (2, 2', 18) and a second main section (3, 3', 19) and at least one transposing junction (4, 4', 21) connecting adjacent ones of the main sections (2, 2', 3, 3', 18, 19). The conductor (1, 10) comprises several partial conductors (7, 8, 15, 16, 17) comprising at least a first partial conductor (7, 15) and a second partial conductor (8, 16), wherein in the first main section (2, 2', 18), the first partial conductor (7, 15) has an outer diameter(d1, d2, d3) which is larger than an outer diameter (d1, d2, d3) of the second partial conductor (8, 16) and, in the second main section (3, 3', 19), the second partial conductor (8, 16) has an outer diameter (d1, d2, d3) which is larger than an outer diameter (d1, d2, d3) of the first partial conductor (7, 15).