Novel electrical machines having separate PM excitation stator

In this paper, novel electrical machines having a separate permanent magnet (PM) excitation stator are proposed based on a partitioned stator (PS) flux reversal (FR) PM (FRPM) machine. Different from the conventional FRPM machines with a single stator, the PS-FRPM machines have two stators with PMs surface mounted in one stator and the armature windings located in another stator. This paper investigates the electromagnetic performance of PS-FRPM machines with 12/10, 12/11, 12/13, and 12/14 stator/rotor-pole, together with the influence of leading design parameters. The torque characteristics of PS-FRPM machines are quantitatively compared with the conventional FRPM machines based on their globally optimized designs. It shows that the PS-FRPM machines can generally produce higher torque when the PMs are thicker and exhibit >56% higher torque density than that of the conventional FRPM machines. Even compared under the same PM volume, the proposed PS-FRPM machines can have larger torque due to better utilization of the inner space. The investigation is validated by both finite-element and experimental results.