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H. Miyazaki, M. Iwakuma, S. Miura, H. SASA, K. Yoshida, S. Sato, I. Sagara, Y. Hase, M. Konno, Y. Sasamori, H. Honda, T. Okabe, H. HIRAI, S. Lee, S. Hasuo, M. Nakamura, N. Mido, K. Adachi, K. Shiohara, T. Izumi, A. Kawagoe, M. Deki, H. Amano, Y. Kawaguchi, T. Yamasaki, High efficiency and high power electric propulsion system for airplane by superconductivity
Development of a REBCO fully superconducting motor and cooling system, Applied Superconductivity Conference 2022, 2022.10, s a measure against global warming, aircraft are also required to have zero emissions. Simply changing the fuel of the current aircraft to liquid hydrogen will increase the volume of the fuel tank and reduce the payload due to the small energy density per unit volume of liquid hydrogen. In order to achieve zero emissions for aircraft, it is necessary to develop a compact, lightweight, and highly efficient electric propulsion system to actually realize distributed ducted fans as well as a blended wing body. The application of superconducting technology is indispensable for reducing the weight of electric propulsion systems. We are developing an electric propulsion system with a total output of 20 MW for 100-200 passenger aircraft such as B737 and A320 using REBCO high temperature superconducting wires. As proposed by NASA, it is a method in which a superconducting generator is rotated by a gas turbine, and the generated power is supplied to a superconducting motor via a superconducting cable and a low-temperature operation inverter. The fuel will be liquid hydrogen in the future. The refrigerant for superconducting systems is subcooled liquid nitrogen at 65 to 70K. Liquid nitrogen is cooled by heat exchange with liquid hydrogen. Three years ago, we successfully manufactured a 1kW fully superconducting synchronous motor by way of trial. The armature was cooled with subcooled liquid nitrogen, and the rotating field was cooled with helium gas which was maintained at a temperature around 70 K with subcooled liquid nitrogen. This time, we have completed the design of a 400kW fully superconducting synchronous motor that follows this structure and are currently manufacturing it. The casing is made of CFRP. Liquid nitrogen is cooled by heat exchange with liquid helium instead of liquid hydrogen. In this paper, the outline of the entire project is introduced and the progress of the current situation is reported.. |
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H. Miyazaki, M. Iwakuma, S. Sasa, S. Miura, K. Yoshida, S. Sato, I. Sagara, Y. Suzuki, M. Konno, H. Hirai, T. Izumi, Fabrication and test of a 400 kW-class fully superconducting synchronous motor using REBCO tape for an electric propulsion system, International Conference on Magnet Technology 28, 2023.09, Advanced electric propulsion systems have been developed by utilizing superconducting technologies to reduce carbon dioxide emissions from aircraft. This study examines the progress in the development of a 400 kW-class fully superconducting synchronous motor using REBa2Cu3O7- (REBCO) tape. REBCO tapes have high critical current densities; thus, they can generate a strong magnetic field with no iron core, permitting the fabrication of small-sized motors compared with conventional motors with copper wires and iron cores. The 400 kW-class fully superconducting synchronous motor comprised the field and armature coils. The field coil was wound with cons-theta-like racetrack distribution to generate a dipole field with no iron core. The maximum magnetic field was 1.45 T when the operating current was 110 A DC. The armature coil comprised six racetracks double pancakes wound with six-strand parallel conductors. The parallel conductors were transposed inside the windings, resulting in a uniform current distribution in each conductor. The motor utilized carbon fiber-reinforced plastic (CFRP) for the casing instead of stainless steel for weight reduction. Foam insulation was adopted to further reduce the mass, in which an adiabatic material was wrapped around the external part of the CFRP casing. The armature coil was cooled using sub-cooled liquid nitrogen (LN2), with high electrical insulation and a stable liquid phase. In contrast, the field coil was cooled by utilizing helium gas instead of LN2 because sealing the LN2 with a magnetic fluid seal is challenging. The motor was tested in a synchronous generator mode and subsequently rotated by utilizing three bipolar power supplies. The motor successfully rotated at 441 rpm when the field current was 72 A, the armature current was 103 Arms, and the frequency was 7.35 Hz.. |
