A New Dual-PM Excited Doubly Salient Machine for Traction Applications

This paper proposes a new dual-PM excited doubly salient machine (DPM-DSM) in which the PMs are employed in both the stator yoke and the slot openings. The proposed design is derived from the existing variable flux PM machine with PMs in stator yoke by adding another layer of PMs in the slot openings. The PMs in both the stator yoke and the slot openings can interact with the armature field to generate electromagnetic torque, and consequently the torque capability of the proposed machine can be improved. Therefore, the proposed machine is very suitable for traction applications which require large torque density. Meanwhile, modular design of the stator can be achieved, which can simplify the manufacturing. The rotor only has salient poles, which is mechanically robust and works in high speed. The FEM-TS coupled method, namely the finite element method coupled with a Tabu search algorithm, is used to find the optimal design of the proposed DPM-DSM. The electromagnetic performance of the proposed machine is comprehensively investigated using FEM. The results show that with the aid of slot PMs the electromagnetic torque of the proposed machine can be increased by 62%.