Design of Fractional-Slot Concentrated Winding Consequent Pole Motor for Ceiling Fans

In recent years, the consequent-pole permanent magnet (CPM) machines have become the attractive solution because of their high permanent magnet utilization ratio. However, because of the introduction of even order harmonics, effects such as asymmetric back EMF and high torque ripple are observed. In this study, a fractional-slot concentrated winding (FSCW) consequent pole permanent magnet machine is analyzed for a low power ceiling fan application. Performance is comparatively assessed against a surface permanent (SPM) motor and a Halbach array assisted permanent magnet (HPM) motor. Moreover, an improved version of conventional CPM, a Halbach array assisted consequent pole permanent magnet (HCPM) brushless DC machine with asymmetric poles, is proposed for ceiling fan application, which has not been reported earlier. It is demonstrated that the asymmetric pole HCPM significantly improves the torque ripple for about the same output torque. All the designs are characterized by 2-D finite element analysis (FEA).