Design of Superconducting AC Propulsion Motors for Hybrid Electric Aerospace

The aerospace industry has ambitious environmental emissions and noise reduction targets that have led to some radical proposals for future aerospace transportation technologies. One of the disruptive technologies identified is hybrid electric propulsion. The use of electrical machines for aerospace propulsion is not a new concept. Fully superconducting machines have the potential to deliver the step-change in specific torque, power and efficiency capabilities required for large civil transport aircraft applications. However fully superconducting machines are still in their infancy. This paper looks at the electromagnetic design of two different stator design concepts for an AC fully superconducting machine for an aerospace distributed fan motor using a benchmark aerospace specification. A benchmark aerospace specification of 1 MW was chosen and the design of a conventional permanent-magnet machine was used to assess the performance of the two equivalent fully superconducting AC motor designs. The AC fully superconducting machine includes superconducting bulk magnets mounted on a conventional rotor core and an MgB2 superconducting wire wound stator in a non-magnetic core. The paper looks at a fully superconducting air-cored stator design to reduce weight and a new yokeless stator design is proposed to reduce the armature losses. The paper will look at the key design issues of the different motor designs in relation to the current aerospace targets for efficiency and power densities.