A novel modular multistage axial-flux permanent magnet machine for electric vehicles

In this paper a novel modular multistage axial-flux permanent magnet machine (MM-AFPMs) is proposed for the drive machine applications in electric vehicles (EVs), which has the features of slotted north-south-pole (NS) topology, segmented and yokeless stator, ellipsoidal similar Somaloy teeth, flexible power and switch circuits. As the most concerned properties in EVs, the excellent speed-extension capability and cogging torque minimization of the new machine are discussed at great length. Both theoretical analysis and finite-element method (FEM) are used to optimize the design of the new machine. Based on a 2kW-1000rpm 10-pole 12-open-slot prototype, the experiments are developed. The results measured by experiments agree well with the ones predicated by 3D FEM, which verifies the conclusions and design.