A Hybrid Analytical Method for Yokeless and Segmented Armature Machine Considering Rotor Shifting and Eccentricity

This paper proposes a hybrid analytical method to analyze rotor shifting and eccentricity in the yokeless and segmented armature (YASA) machine. The quasi-3-D subdomain (SD) method is utilized to calculate the magnetic field distribution accounting for the rotor shifting. The multilayer YASA machine is divided into five SDs considering the bilateral permanent magnet distribution and stator slot depth. Moreover, a suppression technique based on the rotor shifting and superposition method is accordingly proposed by regulating the rotor-shifting value, which is low-cost and will not compromise the output performance. The uneven air gap under rotor eccentricity is modeled via Schwarz-Christoffel (SC) mapping to ease the modeling difficulty of the SD method. The SC mapping yields a complex relative permeance used to modify the flux density predicted by the SD method. The calculation results are compared with finite element analysis (FEA), which shows a good agreement between the analytical and FEA results. The YASA machine is fabricated and experiments are carried out. The experimental results demonstrate the effectiveness of the proposed analytical method.