CNT Composite Busbars for Traction Motor Skin Effect
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Solution Overview
Problem
Existing traction motor busbars face challenges due to the skin effect, which increases effective resistance as the frequency of alternating current increases, limiting their efficiency and performance.
Innovation Solution
A composite conductor is developed, featuring a surface with a first copper tape laminated to it, where the copper tape includes a layer of carbon nanotubes sandwiched between copper layers, enhancing electrical conductivity and reducing resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a single busbar is used to carry high current, then the current carrying capacity is sufficient, but the skin effect increases effective resistance and reduces efficiency
Solution Approach 1:
The busbar is segmented into multiple smaller parallel conductors instead of using a single solid busbar. This segmentation reduces the skin effect by distributing current across multiple surfaces, thereby reducing effective resistance while maintaining sufficient current carrying capacity through the combined cross-section of all segments.
Solution Approach 2:
The invention uses composite conductors combining copper and aluminum materials in a structured arrangement. The copper core provides high conductivity and strength, while the aluminum cladding reduces weight and cost. This composite structure optimizes the balance between current carrying capacity, effective resistance, and mechanical properties.
2Loss of energy
If multiple smaller composite conductors are used to combat skin effect, then effective resistance is reduced, but the device complexity increases
Solution Approach 1:
Multiple copper conductors are merged into a single integrated composite busbar structure with aluminum cladding. This combining approach maintains the low effective resistance benefits of multiple conductors while simplifying the overall device by creating a unified component that can be installed as a single unit, reducing assembly complexity.
Solution Approach 2:
The composite copper-aluminum structure allows multiple conductors to be bundled and treated as a single integrated component. The aluminum cladding unifies the appearance and protection of multiple internal copper conductors, simplifying the overall device structure while maintaining the electrical benefits of segmented conductors.
3Loss of energy
If copper tape with carbon nanotubes is laminated to the busbar surface, then electrical conductivity is enhanced and resistance is reduced, but the manufacturing process becomes more complex
Solution Approach 1:
The invention modifies the surface properties of the busbar by laminating copper tape with embedded carbon nanotubes. This changes the electrical conductivity parameter of the busbar surface, creating a low-resistance pathway for current flow. The carbon nanotubes enhance electron transport, reducing effective resistance without requiring complete restructuring of the manufacturing process.
Solution Approach 2:
The copper tape itself is a composite material combining copper matrix with carbon nanotube reinforcement. This composite structure provides enhanced electrical conductivity and mechanical strength. The lamination process applies this pre-fabricated composite tape to the busbar surface, separating the material synthesis from the assembly process and simplifying manufacturing.
4Quantity of substance
If the busbar cross-section is increased to reduce resistance, then current carrying capacity improves, but the weight and volume increase
Solution Approach 1:
The busbar uses a composite copper-aluminum structure where the lighter aluminum material replaces portions of the heavier copper. This maintains sufficient current carrying capacity through optimized copper distribution while significantly reducing the overall weight. The aluminum cladding provides structural integrity with minimal weight penalty.
Solution Approach 2:
The conductor is segmented into copper and aluminum regions, placing copper where highest current density is needed and aluminum in regions where lower conductivity is acceptable. This strategic segmentation optimizes current carrying capacity per unit weight, reducing overall busbar weight while maintaining required electrical performance.
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 composite conductor achieves a significant reduction in electrical resistance, an increase in ampacity, and improved strength compared to pure copper, while also mitigating the skin effect, thus enhancing the performance of traction motor busbars in both high-frequency and low-speed applications.
Implementation Method 1
a layer of carbon nanotubes sandwiched between a first copper layer and a second copper layer... exhibiting an electrical conductivity 1.0×10^7 Siemens per meter (S/m) or greater
Implementation Method 2
current density tends to be larger near the surface of the busbar and decreases as it approaches the core... This effect, known as the skin effect, increases as the frequency of the alternating current increases
Data Source
AI summary
A composite conductor for a vehicle, a propulsion system for a vehicle, and a method of forming a composite busbar for a vehicle. The composite conductor includes a surface, and a first copper tape laminated to the surface. The composite conductor is electrically conductive exhibiting an electrical conductivity of 1.0×10{circumflex over (7)} Siemens per meter (S/m) or greater. The first copper tape includes a layer of carbon nanotubes sandwiched between a first copper layer and a second copper layer. The composite busbar may be connected to a plurality of windings in the stator of an electric motor.