Overview and Evaluation of Electric Machines for Electric Regional Aircraft Propulsion Systems

The article presents and evaluates the most common topologies of electric machines for use as propulsor drives in regional aircraft. The design, mode of operation, characteristic features and areas of application of the direct current machine, the permanently excited and externally excited synchronous machine, the reluctance machine and the induction machine as well as their topology variations are described. Evaluation criteria derived from aviation-specific requirements are weighted by means of a pairwise comparison. After a pre-selection by exclusion criteria, selected topologies are consequently evaluated. The results show the great potential of radial flux and axial flux permanently excited synchronous machines in terms of power density and efficiency as well as the advantages of the switched reluctance machine due to its simplicity and high level of safety. The challenges identified for future electric machines include high efficiency and power density with varying altitude and thus changing temperatures and ambient pressures, taking into account high system safety and durability. The need for research and further development is emphazised by the average values of the evaluation factors.