Functionally Graded Superconductive Wire for High Torque Density
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Solution Overview
Problem
Existing superconductive rotating machines face challenges in reducing size and weight while increasing torque density, as conventional superconductive wires are not tolerant enough to magnetic fields, limiting current capacity and torque generation.
Innovation Solution
Functionally graded superconductive wires with segments differing in magnetic field, temperature, ac loss, and strain tolerance are used, allowing for enhanced magnetic field capability and increased torque generation by strategically positioning more tolerant segments within high-field regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional superconductive wires (NbTi or Nb3Sn) are used in field coils, then the machine can generate magnetic field and torque, but the magnetic field tolerance is limited and current capacity decreases in high-field regions
Solution Approach 1:
The field coil is divided into multiple segments, each containing wire segments with different superconductive materials (NbTi and Nb3Sn) arranged in specific patterns. This segmentation allows different portions of the coil to handle different magnetic field intensities, with more field-tolerant materials positioned in high-field regions and less tolerant materials in low-field regions, thereby maintaining high current capacity throughout the coil while ensuring reliability in critical high-field areas.
Solution Approach 2:
Different superconductive materials with varying magnetic field tolerances are strategically positioned at different locations within the field coil. Nb3Sn, which has higher magnetic field tolerance, is placed in regions experiencing higher magnetic fields (inner turns), while NbTi is placed in regions with lower magnetic fields. This local differentiation of material properties optimizes the overall performance by ensuring each region operates within its material's optimal tolerance range, thereby maintaining high current capacity without sacrificing reliability.
2Force
If the magnetic field strength is increased to generate greater torque, then torque per rotation increases, but the superconductive material transitions to non-superconductive phase at critical field Hc
Solution Approach 1:
The field coil uses a composite structure combining NbTi and Nb3Sn superconductive materials in the same coil assembly. Nb3Sn, which has higher magnetic field tolerance and can withstand higher critical fields, is positioned in regions where the magnetic field strength is highest. This composite approach allows the coil to generate stronger magnetic fields and greater torque while maintaining superconductive phase stability, as the high-field regions are protected by materials designed to withstand those conditions without transitioning to the non-superconductive phase.
3Power
If more field tolerant superconductive materials are used, then magnetic field capability and torque density increase, but manufacturing cost and price increase
Solution Approach 1:
Instead of using expensive high-field-tolerance materials throughout the entire field coil, the invention applies field-tolerant materials (Nb3Sn) only in specific high-field regions where they are most needed, while using more cost-effective materials (NbTi) in low-field regions. This localized application of premium materials optimizes torque density and magnetic field capability in critical areas while significantly reducing overall manufacturing costs compared to using high-performance materials uniformly throughout the coil.
Solution Approach 2:
The field coil is segmented into multiple sections with different material compositions based on the magnetic field distribution. This segmentation allows the design to optimize performance in high-field regions using Nb3Sn while using more economical NbTi in other regions, thereby achieving high torque density without the prohibitive cost of using expensive materials throughout the entire coil structure.
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 use of functionally graded superconductive wires enables higher current capacity and greater torque per rotation, reducing machine size and weight, and lowering manufacturing costs by optimizing magnetic field tolerance and torque density.
Implementation Method 1
the first wire segment and the second wire segment differ in at least one property selected from the group consisting of magnetic field tolerance, temperature tolerance, ac loss, and strain tolerance
Data Source
Figure 1~2
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AI summary
An electrical component comprises a superconductive wire (10), the wire (10) comprising a first wire segment (12) joined to a second wire segment (14), wherein the first wire segment (12) and the second wire segment (14) differ in at least one property selected from the group consisting of magnetic field tolerance, temperature tolerance, ac loss, and strain tolerance, and wherein the magnetic field tolerance is measured by the relationship of critical current Ic to magnetic field H at a given temperature T below Tc, the temperature tolerance is measured by the relationship of critical current Ic to temperature T at a given magnetic field below Hc, the ac loss is measured by the amount of ac loss versus the frequency and magnitude of applied ac currents and fields, and the strain tolerance is measured by Ic degradation with strain.