Dual stator two-phase permanent magnet machines with phase-group concentrated-coil windings for torque enhancement

Recently, the demand for developing high performance permanent magnet (PM) machines with high torque density and high efficiency are becoming more and more attractive due to the environmental and energy considerations. Notwithstanding the three-phase PM machines are most commonly employed in various industrial and domestic applications benefiting from their well-known high performance, two-phase PM machines are increasingly investigated resulting from their relatively low drive system cost and competitive performance in torque density compared with three-phase PM machines. Furthermore, concentrated windings offering short end-winding and low copper loss have gained more and more interests and been often applied in two-phase machines. However, the reported design for two-phase PM machines with conventional concentrated windings is non-effective to further significantly improve the torque performance. Therefore, in this paper, the novel dual stator two-phase PM machines are proposed for obtaining significant torque enhancement by utilizing phase-group concentrated-coil windings together with an unaligned arrangement of two stators as well as a spoke-type PM array. In order to highlight the advantages of the proposed two-phase PM machines, one three-phase PM machine and one two-phase PM machine with the conventional stator and winding configurations are adopted for comparison based on finite element method (FEM).