Investigation of Novel Composite Stator Permanent Magnet Machines

A novel composite stator permanent magnet (CSPM) machine is proposed, where the half number of tangentially-magnetized permanent magnets (PMs) of flux switching PM (FSPM) machines are replaced by the radially-magnetized PMs. Meanwhile, the concentrated armature coils and the salient rotor are both inherited. The rule of slot/pole number combinations of the proposed CSPM machines is introduced. Moreover, the coordinated effect of the two types of PMs is revealed, and their contributions to electromagnetic characteristics are quantitively separated. A 12-stator-slot/13-rotor-pole-pair CSPM machine is comprehensively compared with a pair of classic FSPM machines. The results show that the CSPM machine has 7.47% and 5.40% higher back-electromotive-forces (back-EMFs), as well as 13.37% and 1.4% higher torques than the 12/13 and 6/13 FSPM counterparts, respectively. Moreover, the CSPM machines benefit from low back-EMF harmonics thanks to the cancellation effects on odd order items, as well as the remarkably low unbalanced magnetic forces on the rotor, and the attractive thermal performance. A CSPM prototype machine is fabricated and tested.