Development of Electric Propulsion System for Aircraft using Superconducting Technologies

The electrical propulsion system has the possibility to be a solution to solve CO2 issues in the field of the airplane. However, the conventional technology by Cu-winding around an Fe-core should lead to the overweight of the rotating machine such as motor, which will make the benefit by the electrification lose. Then, the superconducting technologies can realize the electric propulsion system with light weight due to the extremely high current density comparing the conventional Cu-wire. Through the previous development of the superconducting devices such as motor, transformer and cable, our team in Japan has the necessary key-technologies to manufacture the electrical propulsion system for airplane. The proposing concept using superconducting technologies includes superconducting devices of generator, cable and motors. Especially for the rotating devices such as generator and motor, the fully superconducting machine, which consists of superconducting armature and field coils, will be realized. Based on the background, the feasibility study had taken place for almost one-year of FY2018. In this project, the conceptual designs of superconducting motor, generator and cable were made. Additionally, the 1kW fully superconducting motor was actually manufactured using REBCO coated conductors. The project successfully finished with the reasonable conceptual design for 20MW propulsion system and the confirmation of the operation of the 1kW fully superconducting motor. According to these achievements, a large national project was started in Japan at FY2019. The project includes two large research issues. One is the development for fundamental technologies of elemental functions, which consists of those of rotating machine, cable, cooling system, coated conductors, and low temperature operating semiconductor. The other is the verification of device & system function, which consists of verifications of 250-500kW fully superconducting motor and 0.5-1MWclass propulsion system. Now, the production of the 250-500kW fully superconducting motor is in the final stage. In this paper, the progresses of the current project, which includes the major results in the development for fundamental technologies and the verification of the fully superconducting motor are reported. This work is based on results obtained from a project commissioned by NEDO and METI.