Plastic structure multi-disc axial flux PM motor

High efficiency at full load as well as at partial load and high torque density are the challenging characteristics required by the propulsion system for a solar aircraft. The proposed solution is a multi-disc axial flux PM motor with a mechanical structure made of plastic materials: (a) the multi-disc geometry allows high torque density by increasing the number of air-gap surfaces; (b) the PMs and the (almost) ironless magnetic circuit, cutting the no load losses, allow very high efficiency over the complete working range; (c) the motor structure made of plastic materials, with high thermal and mechanical characteristics, allows further increases in the torque density. The paper presents the motor design and performances.