Electromagnetic Performance Comparison of Doubly Salient PM Machines With Different Stator Iron Core Segments

Abstract

This article compares the electromagnetic performances of doubly salient permanent magnet (DSPM) machines with different stator iron core segments. Since the permanent magnets (PMs) of the DSPM machines studied in this article exist in pairs, the feasible numbers of PMs in the 12/8-pole DSPM machine are 12, 6, 4, and 2, and thus, the corresponding stator tooth number between two adjacent PMs is 1, 2, 3, and 6, respectively. Therefore, the stator iron core segments of the four DSPM machines have different shapes. Furthermore, to improve the average torque, PMs are inserted into the slots, and flux focusing teeth are adopted. All four machines are designed to achieve larger average torque under the fixed copper loss and envelope size. The comparison shows that the DSPM machine with two stator teeth between adjacent PMs exhibits the largest average torque and the smallest torque ripple. Moreover, the DSPM machine with six stator teeth between two adjacent PMs has the optimal PM utilization. To verify the predicted results, a 12/8-pole DSPM prototype with two stator teeth between adjacent PMs is manufactured and tested.