A Novel DC-Excited Doubly Salient Machine with Modular II-Shaped Stator Iron Core

This paper proposes a novel DC-excited doubly salient machine with modular II-shaped stator iron core segments, in which a doubly salient structure is exploited and field windings are placed in the slots between two adjacent II-shaped stator iron core segments. Its electromagnetic paths are symmetrical due to the uniform excitation distribution. In this paper, the number of stator teeth is 12, the number of rotor teeth is chosen as 7 to cancel even order harmonics in the backelectromotive force and the resultant torque ripple is lower. Furthermore, stator teeth can be bent to improve slot area allocation, thus leading to higher torque density. Proposed machines are globally optimized with the maximum average torque under the fixed copper loss and envelope size. The proposed machines embrace superior performance over the conventional variable flux reluctance machine in terms of torque density and efficiency, while retaining a comparable flux regulation capability.