High Power Density Propulsion Motor for Hybrid Electric Aircraft

Abstract

The Civil Aerospace is looking ahead for new solutions that can offer further significant improvement in aircraft efficiencies and emissions. Hybrid Electric Distributed Propulsion (HEDP) aircraft’s configurations have been extensively modelled, and these results show it is possible to obtain notable benefits with some authors claiming that overall fuel savings of more than 70% are possible compared with today’s designs. However, these models depend critically on electrical power networks and machines being able to operate with significantly improved power densities and efficiencies in the aircraft electric plant. In general these multi-megawatt power systems have been used in applications where volume and weight have been secondary considerations and hence new techniques and approaches are now required. A further issue is designing machines to address other constraints required for aircraft installation, for example motors integrating with propulsive systems. Hence for these applications new and evermore performing electrical machine designs are now required. The work showcased in this thesis is meant as a beginning to address these new requirements. Chapter 1 presents the challenges identified and locates the motivation of this work in the more vast application sense of aerospace propulsion. Chapter 2 provides a literature review and initial considerations on the power density increase. Chapter 3 is a collection of methodologies developed for mainly mechanical and initial electromagnetic performance evaluation. Chapter 4 delivers the optimized result for different machines comparison as well as alternative choices of objectives and constraints dictated by the design envelope. Chapter 5 identifies and develops further the chosen candidate: high order effects in the mechanics/rotor-dynamics and rotor losses estimation are thoroughly investigated. Chapter 6 addresses the manufacture choices undertaken and initial tests conducted on the machine. The thesis ends with the conclusions in Chapter 7.