A proposal for a lightweight, large current superconducting cable for aviation

Abstract

More Electric Aircraft (MEA) is one of the most important subjects for designing the next generation of aircraft. Since we cannot ground the electric power systems of a flying aircraft and the air insulation voltage is lower at high altitude, a low voltage, direct current (DC) aircraft electrical system is preferable for a MEA. Since the current must be high to supply high power, we consider high temperature superconducting (HTS) technology because it handles large currents well. We propose a new HTS cable in this paper. The cable uses a stacked conductor, with oppositely directed current in each HTS tape, a structure that has already been shown to be feasible for low voltage cables. It enhances the critical current compared to a single tape conductor, especially for Bi2223 tape. In order to avoid a current imbalance in the stacked conductor, we use the current lead resistance rather than a Roebel conductor design. Then the critical current remains high, and this is confirmed by measurements. The cryogenic pipe will be made of magnesium-lithium alloy, one of the lightest metals available at the present time. We estimate the weight-to-current ratio per unit length to be less than 0.5 kg/A/km at the liquid nitrogen operational temperature of 77 K, lighter than conventional copper cable. If instead we use liquid hydrogen at 20 K, we expect a value less than 0.1 kg/A/km, which is one of the lowest presently achievable values and satisfies the requirements for MEA.

Lightweight and Large-Current HTS Stacked Tape Conductor

“…We originally proposed the stacked conductor for a short power cable, which is lightweight, small in diameter, and low voltage, especially in DC cable applications [4]. Figure 1 shows the stacked conductor's cable cross-section and electric circuit.…”

“…Because of these technical reasons, we proposed a DC cable for aviation [4] with a stacked conductor structure. The current direction of each layer is opposite, and we used the Bi2223 tapes and reported the first experimental results [4].…”

“…Because of these technical reasons, we proposed a DC cable for aviation [4] with a stacked conductor structure. The current direction of each layer is opposite, and we used the Bi2223 tapes and reported the first experimental results [4]. One of the 2 04894OrA3-7 positive results was that the average critical current of the stacked conductor is ~20% higher than the single Bi2223 tape, and therefore, we can make a lighter conductor cable in principle.…”

“…One of the 2 04894OrA3-7 positive results was that the average critical current of the stacked conductor is ~20% higher than the single Bi2223 tape, and therefore, we can make a lighter conductor cable in principle. However, the electric circuit of the stacked conductor tapes was connected in series [4], and all currents of the Bi2223 tape were the same completely in the experiment. Since we usually need a large current for the electric power devices, we should connect HTS tapes of the electric circuit in parallel.…”

Comparison of the Field Trapping Ability of MgB2 and Hybrid Disc-Shaped Layouts

“…Superconductors, with their remarkable ability to trap magnetic fields at levels significantly surpassing those achievable with traditional permanent magnets [ 1 , 2 , 3 , 4 ], play a pivotal role in advancing magnet technology. This unique property has indeed gathered considerable interest for various engineering applications, such as energy storage systems [ 5 , 6 , 7 ] high current machines [ 8 , 9 , 10 , 11 ], magnetic resonance imaging (MRI), and portable magnets [ 12 ], to name just a few. Furthermore, an additional improvement in trapping field ability has been obtained, creating hybrid arrangements wherein ferromagnetic (FM) components are superimposed or integrated into the superconducting (SC) ones [ 13 , 14 , 15 , 16 ].…”