Superconducting Cable Magnetic Shield Reduces Eddy Current Loss
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Solution Overview
Problem
Superconducting cables without a shield layer generate leakage magnetic fields when arranged close to each other, leading to eddy current losses in thermal insulation pipes made of metal materials, which increase the load on refrigeration systems cooling the refrigerant.
Innovation Solution
Incorporating a magnetic shield member with a ferromagnetic layer between the superconducting cables and potential magnetic field sources to redirect and reduce external magnetic fields, thereby minimizing eddy current losses in the thermal insulation pipes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a superconducting cable without a superconducting shield layer is used to reduce cost, then manufacturing cost is reduced, but leakage magnetic field is generated causing eddy current loss in the thermal insulation pipe
Solution Approach 1:
A magnetic shield layer made of ferromagnetic material is introduced as an intermediary between the superconducting cable and the thermal insulation pipe. This magnetic shield layer redirects magnetic field lines, preventing them from penetrating into the metal thermal insulation pipe, thereby eliminating eddy current loss while allowing the cable to operate without an expensive superconducting shield layer
Solution Approach 2:
The invention changes the material parameter of the thermal insulation pipe from metal to non-metallic material. This parameter change eliminates the electrical conductivity of the pipe wall, preventing eddy current formation even in the presence of leakage magnetic fields, thus resolving the contradiction between cost reduction and energy loss
2Productivity
If multiple superconducting cables are arranged close to each other to increase power transmission capacity, then productivity is improved, but magnetic fields from adjacent cables cause eddy current loss
Solution Approach 1:
The magnetic shield layer acts as a mediator between adjacent superconducting cables, redirecting magnetic field lines generated by each cable and preventing them from penetrating into neighboring cables' thermal insulation pipes, thereby enabling high-density cable arrangement without significant energy loss
3Strength
If the thermal insulation pipe is made of metal material to provide mechanical strength, then strength is improved, but external magnetic fields induce eddy current and cause Joule heating
Solution Approach 1:
The magnetic shield layer serves as a protective intermediary between the external magnetic field environment and the metal thermal insulation pipe. It redirects magnetic field lines around the pipe, preventing magnetic flux penetration that would otherwise induce eddy currents and cause Joule heating, while the metal pipe maintains its mechanical strength function
Solution Approach 2:
The invention creates a composite protective structure consisting of the magnetic shield layer (ferromagnetic material) combined with the metal thermal insulation pipe. This composite structure combines the magnetic shielding properties of the ferromagnetic layer with the mechanical strength of the metal pipe, achieving both protection against eddy current loss and structural integrity
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 magnetic shield effectively reduces eddy current losses in the inner pipes of the thermal insulation pipes, lowering the refrigeration load by shielding the superconducting cables from external magnetic fields and maintaining efficient cooling.
Implementation Method 1
a magnetic shield member disposed between the superconducting cable and a magnetic field generating cable that applies a magnetic field to the superconducting cable, for shielding the superconducting cable from the magnetic field
Implementation Method 2
The magnetic shield member has a ferromagnetic layer made of a ferromagnetic material
Implementation Method 3
A vacuum is produced in a space between the inner pipe and the outer pipe to form a vacuum thermal insulation layer in this space
Implementation Method 4
refrigerant (liquid nitrogen for example) is flown in the thermal insulation pipe to thereby cool the superconducting layer
Implementation Method 5
induced current which is opposite in direction and substantially identical in magnitude to the current flowing in the superconducting conductor layer flows in this superconducting shield layer. A magnetic field generated by the induced current cancels a magnetic field generated from the superconducting conductor layer
Implementation Method 6
there is a possibility that the magnetic field applied to the thermal insulation pipe causes an eddy current and thereby Joule heating
Implementation Method 7
causes an eddy current and thereby Joule heating, resulting in an eddy current loss
Data Source
AI summary
A superconducting cable line and a thermal insulation pipeline with a low load on a refrigerator cooling refrigerant are provided. The superconducting cable line includes a superconducting cable which includes: a cable core having a superconducting conductor layer; and a thermal insulation pipe housing the cable core and having an inner pipe to be filled with refrigerant and an outer pipe disposed outside the inner pipe. The superconducting cable line also includes a magnetic shield member in a plate shape disposed between the superconducting cable and a magnetic field generating cable configured to apply a magnetic field to the superconducting cable, the magnetic shield member being configured to shield the superconducting cable from the magnetic field. The magnetic shield member has a ferromagnetic layer made of a ferromagnetic material, and the magnetic shield member is electromagnetically independent of a different member made of a ferromagnetic material.