Influence of PM- and armature winding-stator positions on electromagnetic performance of novel partitioned stator permanent magnet machines

Since the permanent magnets (PMs) and armature windings of partitioned stator (PS) PM machines are located in two separate inner and outer stators, their positions can be exchanged to optimize the space utilization, especially in radial field rotating machines. Therefore, in this paper, the influence of PM and armature winding stator positions on the electromagnetic performance of PS-PM machines is investigated based on the novel PS-PM machines (PS-PMMs) with surface-mounted PM (SPM) stator. Similar to the single-stator surface-mounted PMMs (SS-PMMs), flexible rotor pole number, bipolar phase flux linkage, and symmetrical phase back electromotive force (EMF) are also obtained in PS-PMMs. Based on the same 12/10 stator/rotor pole number combination, PS-PMM-I (PMs located in the inner stator) and PS-PMM-II (PMs located in the outer stator) exhibit 120% and 160% higher phase back EMFs as well as 120% and 139% larger average torques, respectively, than the SS-PMM together almost without scarifying the PM utilization efficiency under the same machine size and the same rated copper loss. Further, the proposed PS-PMM-IIs have both higher phase back EMFs and larger average torques than PS-PMM-Is among all the main stator/rotor pole number combinations. Meanwhile, for both PS-PMM-Is and PS-PMM-IIs with 12-pole stator, the machines with the 11-pole rotor exhibit the optimal torque capabilities. Moreover, the reluctance torque is also negligible in the proposed PS-PMMs due to very low saliency ratio. The analyses are validated by experiment results of the prototype machine.