Evolution and Comparison of Two Axial-Flux PM Machines for All-Electric Aircraft Propulsion

This article proposed, optimized, and compared two dual-rotor axial-flux permanent magnet (PM) machines for all-electric aircraft (AEA) propulsion. First, the design requirements are determined, and the initial structures of the yokeless and segmented armature (YASA) machine and the axial-flux vernier PM (AFVPM) machine are designed with identical outer radius, inner radius, and axial length. Several features, including the Halbach array and PM skewing, are introduced to improve power density and efficiency. Then, to reduce the computational burden of finite element analysis (FEA), the surrogate models of machines are constructed by Box-Behnken design (BBD). The electromagnetic performances, such as induced voltage, torque characters, and efficiency of the proposed machines, are simulated. Subsequently, the discussions are carried out, where the strength and weakness of the two machines are evaluated. Finally, it is concluded that the YASA machine is a superior choice for AEA propulsion due to its higher output torque, power density, torque density, and efficiency when compared to the AFVPM machine.