Design and Build of a Mass Critical, Air-cooled Transverse Flux Machine for Aerospace

Electric motors are becoming increasingly utilized in aircraft, replacing traditionally mechanical or hydraulic auxiliary systems to realize improvements in mass, control and efficiency. Aerospace motor design has the unique characteristic that mass and, therefore, torque density is of critical importance. For low maintenance, non-safety critical components, which are only used for short durations of the flight cycle, efficiency also becomes less important, whilst eliminating an external cooling circuit and gearbox will further benefit mass constraints. This paper considers the design of a high torque density machine in order to meet a specification for an aerospace application with a stringent mass target. As mass is reduced, thermal capability becomes critical and detailed thermal models, along with simulation results, are presented for operational characteristics.