To reduce carbon dioxide emissions from aircraft, an electric propulsion system is attracted. Regarding this problem, we are developing a superconducting propulsion system with superconducting synchronous motors and generators with a high output density compared to conventional ones. For aircraft propulsion systems, it is a crucial point to higher the output density of the superconducting motor. As the output is proportional to the revolution speed, we apply a saddle-shaped winding coil to the field coil of the motor using REBCO wires. The coil is directly replaced and fixed on the shaft, hence the mechanical strength of the rotor with the coils required in terms of a high revolution can be stronger than the rotor with the conventional racetrack coils. Thus, it is essential to investigate the effect that the end part of the saddle-shaped coil on the output of the motor. The coil end must be shorter than an accelerator application. The end part of the saddle-shaped coil is generally longer than the conventional racetrack coil since REBCO wire is tape-shaped. That results in the increase of the axial length and the weight of the motor. However, it is necessary to design the coil end so as not to degraded beyond the critical torsion of the REBCO tapes. First, we designed the saddle-shaped field coil so that the coil end contributes to the output of the motor. We calculated the output by the three-dimensional (3D) finite element analysis. In this paper, we proposed the design of the saddle-shaped field coil where the coil end contributes to the output.
This work was supported by the New Energy and Industrial Technology Development Organization (NEDO) under Project JPNP15005.
Keywords: superconducting synchronous motor, REBCO, saddle-shaped coil