Transposed Partial-Conductor Layout for AC Skin Effect Reduction
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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, leading to inefficient use of the conductor's cross-section and increased ohmic losses.
Innovation Solution
A conductor design with at least two main sections and a transposing junction, where partial conductors with varying outer diameters are electrically insulated from each other, allowing current to flow closer to the center and further from the center in alternating sections, effectively canceling out magnetic flux and minimizing the skin effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If solid metallic rod conductors are used for AC current, then the conductor structure is simple and rigid, but the skin effect limits current transmission to the outer layer, resulting in inefficient use of cross-section and increased ohmic losses
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, and their combined effect utilizes the full cross-section efficiently while minimizing skin effect through the transposing junction design.
Solution Approach 2:
The transposing junction enables dynamic switching of the electromagnetic field distribution along the conductor length. By periodically transposing the partial conductors, the magnetic flux linkage changes dynamically, canceling out the skin effect and enabling uniform current distribution across the entire cross-section.
2Power
If large-diameter tubular conductors are used to increase current capacity, then the diameter reaches decimeters for 50-60 Hz currents of tens of kA, but only a very small part of the total cross section is used for transmitting current
Solution Approach 1:
The large-diameter conductor is segmented into multiple partial conductors with varying outer diameters. This segmentation allows each partial conductor to be optimally sized and positioned, ensuring that the entire cross-section of the assembly is effectively utilized for current transmission without the waste inherent in single large-diameter tubular conductors.
Solution Approach 2:
Different partial conductors have different outer diameters, creating local variations in the electromagnetic field distribution. This local quality variation ensures that current is distributed uniformly across the entire cross-section, with each region contributing efficiently to current transmission.
3Loss of energy
If stranded sub-conductors are rolled into triangular cake-slice shape and assembled (Milliken conductor), then the skin effect is reduced through wire transposition, but the solution is specific for stranded-wire conductors and not applicable to rigid conductors of solid metal
Solution Approach 1:
The transposing junction creates a dynamic configuration where partial conductors change positions along the conductor length. This dynamic transposition mechanism achieves skin effect reduction similar to Milliken conductors but is adapted for rigid solid metal conductors, providing versatility across different conductor types.
Solution Approach 2:
The conductor combines multiple partial conductors of different diameters with varying outer radii, creating a composite structure. This composite design achieves the skin effect mitigation of stranded conductors while maintaining the rigidity and structural integrity of solid metal conductors.
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 enables almost full utilization of the conductor's cross-section for current transmission, reducing AC resistance and increasing current capacity by up to 130% without increasing ohmic losses.
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
Implementation Method 2
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
Implementation Method 3
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
Data Source
AI summary
A conductor for conducting electric current has along its length at least two main sections comprising at least a first main section and a second main section and at least one transposing junction connecting adjacent ones of the main sections The conductor comprises several partial conductors comprising at least a first partial conductor and a second partial conductor wherein in the first main section the first partial conductor has an outer diameter which is larger than an outer diameter of the second partial conductor and, in the second main section the second partial conductor has an outer diameter which is larger than an outer diameter of the first partial conductor.