Comparison of Single Air Gap and Dual Air Gap Axial Flux Permanent Magnet Machines for High Torque Applications

The pursuit of environmental protection and low noise has led to growing interest in electric aircraft development. Axial flux permanent magnet machines (AFPMMs) exhibit strong competitiveness in electric aircraft propulsion system owing to the advantages of high torque density and short axial length. Moreover, the axial parallel arrangement of AFPMM stator and rotor reduces the complexity of multilayer structure design. This paper presents three AFPMM topologies, single stator single rotor (SSSR), dual stator single rotor (DSSR), and single stator dual rotor (SSDR), designed according to machine requirements for electric aircraft. Finite element analysis (FEA) is employed to conduct comprehensive evaluations, including detailed comparisons of no-load performance, load performance, rotor deformation, and temperature distribution. The analysis results demonstrate that the DSSR topology achieves the highest output torque and overload capability with minimal rotor deformation. Although its torque ripple is slightly higher, it remains well below the specified requirement, making DSSR topology most competitive among the three topologies.