Novel fault-tolerant stator structure for modular PMSMs with fractional-slot overlapping winding

Permanent magnet synchronous machines (PMSMs) equipped with dual three-phase (DTP) fractional-slot overlapping windings (FSOWs) are characterized by stator modularization, low rotor losses and easy manufacturing. However, the overlapping between the adjacent phase windings may cause poor magnetic insulation in PMSMs, which is undesirable in fault-tolerant applications. This paper proposes a type of novel stator structure, in which flux barriers are inserted in stator yokes of PMSMs to realize low mutual inductance between the adjacent phase windings in DTP FSOWs. The proposed stator structure is described in detail, and the principle of depressing the mutual coupling between the adjacent phase windings is also explained. In addition, the main electromagnetic characteristics of a 24-slot 14-pole DTP FSOW PMSM employing the proposed stator structure with flux barriers are compared with those of the counterparts using the conventional stators without flux barriers.