Reduction of Open-Circuit DC Winding Induced Voltage and Torque Pulsation in the Wound Field Switched Flux Machine by Stator Axial Pairing of Tooth-Tips

In this paper, stator axial pairing of tooth-tips is proposed to suppress the DC winding induced voltage and torque pulsation in the wound field (WF) switched flux (WFSF) machine. The stator is divided into two segments axially, whilst two segments have different arc of tooth-tips. The proposed technique can suppress the rated on-load torque ripple from 17.91% to 6.99%, reduce the peak-to-peak value of cogging torque by 90.1% from 5.14 Nm to 0.48 Nm, and reduce the open-circuit DC winding induced voltage by 84.4% from 39.79 V to 6.21 V. Although the efficiency of the machine is slightly reduced from 81.5% to 80.7%, the average torque can be maintained by >95%.