Comparative Study of Novel Doubly-Fed Doubly Salient PM Machines with Different Stator/Rotor-Pole Number Combinations

This article presents a novel doubly fed doubly salient permanent magnet machine (DFDSPMM) with armature windings wound around stator and rotor teeth. Compared with the conventional doubly salient permanent magnet machine (DSPMM), this machine locates an extra winding in the rotor slots as armature winding to fully use its rotor slot space, thus leading to an increase in the output torque. The structure and operational principle of the proposed machine are analyzed at first. Then, the feasible stator/rotor-pole number combinations are discussed. Furthermore, the electromagnetic characteristics of the investigated machines are predicted based on the 2-D finite element (FE) analysis. It shows that higher torque density and lower cogging torque can be achieved by the proposed DFDSPMMs with improved stator/rotor-pole number combinations. Moreover, the proposed DFDSPMMs are compared against a surface-mounted permanent magnet machine (SPMM) to reveal comprehensive performance. Finally, the prototype is built and tested to validate the 2-D FE predictions.