An Improved Biased-Flux Doubly Salient Shifted Permanent Magnet Motor

This paper introduces a new type of biased flux permanent magnet (BFPM) motor in which the PMs are located in the yoke and slot opening positions with the aim of torque ripple reduction and higher average torque compared to the doubly salient PM (DSPM) structures and better thermal management compared to flux-reversal PM (FRPM) and flux-switching PM (FSPM) topologies. In this structure the PMs in the yoke and slot opening positions are shifted with respect to each other which provides lower reluctance path for armature flux. Moreover, the efficiency of this structure is improved compared to the conventional BFPM. The PMs are placed circumferentially in the stator and the stator modules are mechanically isolated from each other which increase the fault tolerance property of the structure during short-circuited phase operation. The design optimization process along with electromagnetic performance is assessed with finite element method (FEM) and the no/full-load characteristics are also provided. Moreover, a comparative study is conducted to better understand the advantages of the proposed structure.