New approach to suppress torque ripple and improve torque output for wound-excited doubly salient machine

Wound-excited doubly salient machine (WEDSM) has a broad application prospect in the field of aircraft due to the advantages of simple and reliable structure, convenient manufacture and flexible adjustment of the air gap flux. However, the disadvantage of large torque ripple has also restricted its scope of application. The cogging torque of the machine is obtained from simulation and analyzed in details, which is proved to be one of the main factors that cause the torque ripple. Based on the back EMF waveforms of the machine, a novel three-phase nine-states control strategy (TPNS) for WEDSM is proposed and investigated in this paper. This novel control strategy can partially reduce the negative cogging torque. The above theoretical analysis is verified by the simulations and experiments with a 18kW 12/8-pole WEDSEM prototype.