Cladded Copper Foil Windings for High-Frequency AC Resistance
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Solution Overview
Problem
Conventional electric motor conductor wires experience significant AC resistance increases due to the skin effect at high frequencies, leading to inefficiencies in high-frequency applications, as the current tends to concentrate near the surface of the conductor, resulting in increased resistance and reduced ampacity.
Innovation Solution
The method involves folding, stacking, or rolling ultra-conductive copper foils coated with carbon nanotubes, then cladding with copper or aluminum, and plastically deforming them into hairpin windings to reduce resistance and enhance ampacity, utilizing the enhanced conductivity of ultra-conductive copper materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional solid conductor wires are used, then the current flows through the conductor, but the skin effect causes current to concentrate near the surface at high frequencies, increasing AC resistance
Solution Approach 1:
The patent divides the solid conductor into multiple thin-walled hollow strands, each with diameter less than the skin depth. This segmentation allows current to flow uniformly through all strands rather than concentrating at the surface, eliminating the skin effect and reducing AC resistance while maintaining high-frequency performance
Solution Approach 2:
The patent uses composite construction with multiple hollow strands bundled together, where each strand is designed with specific dimensional characteristics (diameter < skin depth). This composite approach combines the benefits of reduced skin effect with structural integrity and flexibility needed for motor applications
2Loss of energy
If Litz wire with multiple round wire strands is used, then skin effect is reduced, but the bundle does not result in a dense conductor due to excess empty space between wires
Solution Approach 1:
The patent segments the conductor into multiple thin-walled hollow strands that can be tightly packed. The hollow structure and thin walls allow for more efficient packing compared to solid round wires, reducing empty space while maintaining the segmentation benefits for reducing skin effect and AC losses
Solution Approach 2:
The thin-walled hollow strand structure acts as a flexible shell that can be densely packed into the conductor bundle. The thin walls minimize the non-conductive material while maintaining the hollow structure's electrical benefits, achieving both high density and reduced AC losses
3Reliability
If ultra-conducting copper foil with carbon nanotubes is folded and cladded, then resistance is reduced and ampacity is increased, but the manufacturing process becomes more complex
Solution Approach 1:
The patent uses composite ultra-conducting copper foil containing carbon nanotubes, which provides enhanced electrical conductivity and ampacity. The carbon nanotube-copper composite structure achieves superior electrical properties while the folding and cladding processes integrate these advanced materials into the final conductor product
Solution Approach 2:
The manufacturing process uses nested structures where ultra-conducting copper foil is folded into multiple layers, then cladded with additional copper or aluminum layers. This nested construction method systematically builds the final conductor with enhanced properties while organizing the complex manufacturing steps in a structured sequence
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 achieves a >5% reduction in resistance, >10% increase in ampacity, and >10% improvement in strength compared to commercial pure copper, effectively mitigating skin and proximity effects in high-frequency electric motor applications.
Implementation Method 1
Ultra-conducting copper (UCC) tapes/foils (∼25 um thick) are first folded, stacked or rolled into the cylindrical or cubic roll shape and then cladded with either copper or aluminum on the outer perimeter
Implementation Method 2
After cladding, the UCC/Cu or UCC/Al bars are further plastically deformed by drawing or extrusion to produce the conductor wire/bar/cable with the geometry and dimensions for the electric motor applications
Implementation Method 3
AC current flowing through a single wire conductor increasingly pushes the current toward the surface 'skin' of the conductor as frequency increases. Skin effect is defined as the tendency of an AC current to distribute in a non-uniform manner within a magnet wire such that the current density is largest near the surface of the conductor
Data Source
AI summary
A method of making a conductor includes folding/stacking/rolling an ultra-conducting copper foil into a multiple layer folded/stacked/rolled ultra-conducting copper foil. Cladding the multiple layer folded/stacked/rolled ultra-conducting coper foil with one of copper and aluminum into a cladded folded/stacked/rolled ultra-conducting copper foil and plastically deforming the cladded folded/stacked/rolled ultra-conducting copper foil into one of a cladded ultra-conducting copper wire, bar, and cable.