Torque Performance Improvement of Doubly Salient Electromagnetic Machine by Harmonic Current Injection With Optimized Magnetomotive Force Ratio

The doubly salient electromagnetic machine (DSEM) has simple and reliable structure while suffering from the problem of torque ripple due to the salient pole structure. In order to improve the torque performance, this paper proposes a collaborative optimization method of harmonic current injection and proportion of the armature magnetomotive force (MMF) and field MMF based on the optimized rotor pole arc coefficient. The theory of torque generation and the influence of rotor pole arc coefficient on torque characteristics are analyzed. The relationship between the copper loss and the total MMF is investigated. The influence of MMF proportion on the average torque and torque ripple is studied. The effect of harmonic current injection on torque performance is further analyzed on the basis of the optimized rotor pole arc coefficient. Finally, the 12/10-pole DSEM prototype is developed and the experiment is conducted to verify the analysis.