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In this article, a novel multiple three-phase PM assisted synchronous reluctance machine with delta windings is proposed for enhanced fault tolerance. The delta connected windings offer an additional degree of freedom of the phase currents. Hence, this machine drive could provide higher torque under phase open-circuit condition. More importantly, the delta windings inherently contain zero sequence current path and could help reducing the turn fault current in the event of the most challenging turn short-circuit fault. Owing to the zero sequence current, the residual flux linkage of the fault turn is more effectively nullified leading to lower fault current. The proposed machine performance together with fault tolerant capability under various fault scenarios are investigated and compared with the star connected winding machine by detailed finite element simulation and experimental tests. It shows that the two machines have the same performance under healthy condition whilst the delta winding machine exhibits higher fault tolerance. These advantages are achieved simply by changing the winding connections without any extra cost. Thus, it is more favorable for the fault tolerant applications. [ABSTRACT FROM AUTHOR]

Stator axial pairing of tooth tips is proposed in this article to suppress the open-circuit dc winding induced voltage and torque pulsation in the wound field switched flux machine. In the proposed method, the stator is divided into two segments axially and these two segments have different arcs of tooth tip. The finite element analysis results show that the proposed technique can reduce the on-load torque ripple from 17.91% to 6.99%, reduce the peak-to-peak value of cogging torque by 90.66% from 5.14 N·m to 0.48 N·m, and reduce the peak-to-peak value of open-circuit dc winding induced voltage at 1500 r/min by 84.39% from 79.58 to 12.42 V. Although the efficiency of the paired machine is slightly reduced from 84.93% to 84.11%, the average electromagnetic torque does not deteriorate by more than 5%. The paired machine is prototyped and tested, and the experimental results validate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

This article proposes a new axial dual-stator flux-switching permanent magnet (FSPM) machine for high-speed applications. The machine adopts a fractional slot distributed winding, which has a higher winding factor, efficiency, and torque density. First, the high-speed FSPM machine topology and operating principle are introduced. By employing the winding complementarity principle, the unfavorable even harmonics of a single stator in the FSPM machine can be counteracted, resulting in an essentially sinusoidal permanent magnet (PM) flux-linkage as well as effectively reduced cogging torque and torque ripple. Second, based on the 3-D finite element method (FEM), both the no-load and on-load electromagnetic performances are obtained. Compared with the other three FSPM machines, the advantages of the proposed machine are highlighted. Finally, a high-speed FSPM prototype is manufactured and a test platform is built to measure the no-load and on-load performances, which verifies the theoretical analysis and simulated results. [ABSTRACT FROM AUTHOR]