Speaker
Description
The regular partitioned stator flux-switching permanent magnet (PS-FSPM) machine integrates both permanent magnets (PMs) and armature windings within a single stator, providing significant space utilization for both the inner and outer stators. However, the PMs on the inner stator limits torque enhancement to adjustments in the pole arc coefficient. To overcome this limitation, a PS-FSPM machine embedded with radially magnetized PMs (NN-SS-NN alternating arrangement) on the outer stator is proposed. Under the same winding configuration and rotor tooth count, the PMs on both the inner and outer stator exhibit flux switching and flux reversal effects, respectively. By exploiting the flux coupling between these two effects in the air gap, the amplitude of the air gap flux density is increased, thereby improving the torque performance.
Based on the analytical model of permeability-magnetomotive force, the effects of flux switching effect and flux reversal effect are studied in this paper. Although the amplitude of the air gap flux density harmonics generated by these two effects are different, the harmonic orders remain consistent. Notably, the flux switching effect has a larger amplitude on the low-order harmonics, whereas the flux reversal effect has a higher high-order harmonic amplitude. Then, the equivalent magnetic circuit method is used to reveal the contribution of air gap flux density to the no-load flux linkage, and the effective coupling mechanism of the two effects in the total no-load flux linkage is verified. Under the load condition, the flux reversal effect generated by the tangentially magnetized PMs not only significantly enhances the amplitude of the 4th, 10th and 15th effective working harmonics, but also contributes to the amplitude of the 21st, 27th, 28th and 33rd high-order working harmonics. This phenomenon is consistent with the analysis of the magnetic flux density distribution at no-load condition, resulting in an improvement in output torque. Subsequently, global optimization is performed using the Non-dominated Sorting Genetic Algorithm II (NSGA-II) to determine the optimal parameter values for both the regular and proposed machines. During the optimization process, the number of PMs is constrained to be identical for both two configurations.
Through finite element analysis, the magnetic flux distribution above the embedded PMs in the outer stator teeth is concentrated, which can lead to local saturation. To mitigate this phenomenon, a chamfered stator tooth structure is employed to alleviate saturation. Under the condition of 2 times overload, the PMs of proposed machine exhibits negligible demagnetization. Additionally, in comparison to the regular PS-FSPM machine, the proposed machine demonstrates enhancements in both power factor and efficiency. Specifically, the output torque is improved by 20.55%, while the torque ripple is reduced to 2.67%.
