Design Optimization of Rotor Bridge and Fixing Hole for Spoke-Type PMSM

This article investigates the performance of the spoke-type permanent magnet synchronous motors (PMSMs) for driving systems. The electromagnetic performance of the PMSMs with different rotor bridges and fixing holes is studied, including the no-load characteristic, cogging torque, output torque, and torque ripple. The structures of the rotor bridge and location of the fixing holes in the rotor core are optimized to increase the output torque capability. The results show that the output torque of the single-side bridge is increased due to the reduction of the leakage flux compared with the double-side bridge structure. The motor with the inner side bridge design has the highest output torque. Furthermore, the mechanical strength of the three rotors at the maximum speed is investigated by finite-element analysis (FEA) to verify the feasibility of the structures. Finally, two 3000 r/min 10 kW prototypes have been manufactured and the experimental results validate the analysis methods in this article.