Torque Ripple Reduction of a Doubly Salient Electromagnetic Machine Using Harmonic Current Injection with Optimized Magnetomotive Force

The doubly salient electromagnetic machine (DSEM) has the advantages of simple and reliable structure while suffering from the problem of torque ripple due to the salient poles. In order to reduce the torque ripple and improve the torque performance, this paper proposes a harmonic current injection method combined with the optimized proportion of the armature magnetomotive force (MMF) and field MMF. 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 and the optimized MMF proportion is obtained at the fixed copper loss. The effect of harmonic current injection on torque performance is further analyzed on the basis of the optimized MMF proportion. The finite element analysis (FEA) result shows the torque ripple of the 12/10-pole DSEM is decreased more than 50% and the average torque keeps nearly unchanged after injecting the 5
^th
or 7
^th
harmonic current under the optimized MMF proportion, and the loss increment after the harmonic injection is less than 3%.