Twisted Superconductor Cable Reducing Flux Coupling
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Solution Overview
Problem
Current high-temperature superconductor (HTS) cables face challenges in achieving high current capacity without significant AC and magnetic flux coupling losses, particularly in flat tape shapes, and struggle to efficiently transmit both AC and DC power with minimal cryogenic losses.
Innovation Solution
A torsionally twisted multi-layer tape conductor stack with a rectangular cross-section, using YBCO, BSCCO, or MgB2 tapes, bonded or unbonded, enclosed in electrically or non-electrically conducting sheaths, and cooled by a coolant within the sheath, to minimize strain and flux coupling losses, allowing for higher current transmission in both AC and DC applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If flat HTS tapes are arranged in parallel to increase current capacity, then current carrying capability is improved, but magnetic flux coupling losses increase due to loop circuits formed among the tapes
Solution Approach 1:
The cable is divided into multiple independent strands, each containing HTS tapes arranged in a specific configuration. These strands are then transposed relative to each other, breaking the continuous loop circuits that cause flux coupling. The segmentation of the conductor into discrete transposable strands eliminates the harmful flux loops while maintaining high current capacity through parallel tape arrangement.
Solution Approach 2:
The cable employs a dynamically transposed structure where strands are twisted or transposed along the length of the cable. This dynamic arrangement changes the relative positions of HTS tapes over time and space, preventing the formation of stable flux coupling loops. The transposition technique continuously redistributes the magnetic flux paths, reducing cumulative flux coupling losses while maintaining high current carrying capability.
2Loss of energy
If transposition technique is used to reduce magnetic flux coupling, then flux coupling losses are reduced, but the technique cannot be applied to flat tape-shaped HTS superconductors
Solution Approach 1:
The invention adapts the transposition technique specifically for flat tape geometry by creating local configurations where HTS tapes are arranged in layers within strands, and these strands are then transposed. The local arrangement of tapes within each strand is optimized for flat geometry, while the overall transposition of strands provides the flux coupling reduction. This localized adaptation allows transposition to work effectively with flat tapes rather than requiring circular wire geometry.
Solution Approach 2:
The invention transitions from two-dimensional flat tape arrangement to a three-dimensional transposed strand structure. By stacking flat tapes in layers within strands and then transposing these strands along the cable length, the solution adds a third dimension (the transposition direction) to the originally planar tape arrangement. This dimensional transformation enables flux coupling reduction techniques to be applied to flat tape geometries that cannot be directly twisted like circular wires.
3Power
If HTS cables are designed for high current transmission, then power transmission capability is improved, but cryogenic losses increase
Solution Approach 1:
The invention introduces an intermediary cooling structure where coolant flows through channels formed by the transposed strand configuration. The transposed strand structure creates natural coolant flow paths that efficiently remove heat from the HTS tapes. This intermediary cooling mechanism, enabled by the specific geometric arrangement of transposed strands, allows high current transmission while minimizing cryogenic losses through enhanced heat transfer from the superconducting tapes to the coolant.
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 solution enables high current transmission with reduced cryogenic and magnetic flux coupling losses, suitable for both AC and DC power applications, including large-scale DC power transmission systems, by optimizing the twisting and bonding of superconductor tapes within a compact cable structure.
Implementation Method 1
cooled by a coolant within the sheath
Implementation Method 2
coolant within the sheath
Implementation Method 3
flux couplings created in the loop circuits among the superconducting wires generate significant heat of resistive and magnetic hysteresis losses
Implementation Method 4
High Temperature Superconductor (HTS) wires of BSCCO-2223, BSCCO-2212 and YBCO
Data Source
AI summary
Superconductor cable having a plurality of flat, tape-shaped ribbon superconductor wires assembled to form a stack having a rectangular cross section, the stack having a twist about a longitudinal axis of the stack. Multiple superconductor cables including twisted stacked-cables of the flat-tape-shaped superconductor wires, and power cable comprising the twisted flat-tape stacked cables are disclosed. Superconducting power cable disposed within and separated from an electrical insulator with a space passing cryo-coolant between the superconducting cable and insulator is also disclosed.