Optimized Stator/Rotor-Pole Number Combinations for Torque Ripple Suppression in Four-Phase Doubly Salient PM Machines

Some optimized combination of stator/rotor-pole number are presented in this essay with a view to suppressing the torque ripple in four-phase doubly salient PM machines (DSPMMs). Firstly, the combination of stator/rotor-pole number is discussed to reveal its principle of impact on cogging torque and back-electromotive force (back-EMF). Then, the related features in three DSPM machines with 16/12-, 16/11-, and 16/13-pole number combinations are compared in this essay, including electromagnetic characteristics as no-load flux linkage, cogging torque, back-EMF, losses, and efficiency. It can be found that compared with the conventional 16/12-pole combination, the four-phase DSPMMs with the proposed 16/11and 16/13-pole combination benefit from smaller cogging torque, more symmetrical and sinusoidal back-EMF. Additionally, smoother electromagnetic torque could be thus gained.