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

This paper 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 location of the fixing holes in the rotor core is 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 inner side bridge design of three rotor structures has the highest output torque but will lead to a larger torque ripple. Furthermore, the mechanical strength of the different rotors at the maximum speed is investigated by finite-element analysis (FEA) to verify the feasibility of the structures. Finally, a 3000r/min 10kW prototype has been manufactured and the experimental results validate the analysis methods in this paper.