Electric Propulsion Units in aviation - approach for a mechanical permanent magnet rotor design and the related manufacturing concept

Electric propulsion units are key components for hybridization and electrification of aviation enabling decarbonization and emission reduction. This application is characterized by significant requirements regarding reliability and power density. This paper deals with a specific mechanical rotor design for Electric Propulsion Units configured as Halbach array and its related manufacturing process. First, existing rotor configurations of electric propulsion units are discussed. Based on this analysis optimization potentials regarding air gap minimization, cooling and retaining of centrifugal forces are introduced. The derived reference design compromises a modular setup of the magnetic active part including combinations of form fit and adhesive bond for all relevant interfaces. The individual advantages and disadvantages of the design as well as further optimization potentials are evaluated based on simulative and experimental investigations. The selected design correlates with a specific assembling and magnetization process which is also discussed. Due to a high number of single parts the assembling is performed as multistage process. The magnetization is conducted applying a sub-assembly strategy to avoid manufacturing problems. Finally, an outlook is given with focus set on the aviation compliant certification process.