Rotor Optimization and Electromagnetic Performance Comparison of the 10- and 14-pole Wound-Field Flux Switching Machines

This paper comparatively analyzes the electromagnetic performance of optimized 12/10 and 12/14 wound-field flux switching machines (WFFSMs). Finite element analysis (FEA) integrated with a genetic algorithm (GA) is used to op-timize the rotor geometry and minimize torque ripple. The 12/14 WFFSM demonstrates significant improvements over the 12/10 WFFSM in terms of 27.5% lower torque ripple and 15.7% higher average torque attributed to its higher rotor pole number. However, the 12/14 WFFSM experiences higher core losses and a lower power factor due to increased core saturation from the shorter rotor pitch. Further analysis shows the 12/14 WFFSM achieves slightly higher efficiency (+0.4%) owing to increased output power despite higher core losses. Additional skewing is shown to further reduce torque ripple in the 12/14 WFFSM by 66% while maintaining torque capability. In conclusion, the 12/14 WFFSM with an optimized rotor outperforms the 12/10 WFFSM electromagnetically but careful consideration of the trade-offs is necessary when selecting the rotor pole number for targeted applications. This study provides useful insights into designing higher performance non-PM WFFSMs.