Comparative Studies of Fractional/Integer-Slot Consequent Pole Permanent Magnet Machines

Abstract

This paper compares several different consequent-pole permanent magnet machines (CPM) with fractional-slot (FS) concentrated-winding and integer-slot (IS) distributed-winding. The electromagnetic performance of the proposed machines such as the open-circuit air-gap flux density, back-EMF, cogging torque, on-load torque, inductances, losses and torque/power-speed characteristics are compared by 2D finite element analysis. The reason about the existence of the even-harmonics in the phase back-EMF of the CPMs is explained from the perspective of winding factor. It is also found that the FS-CPMs have better flux weakening capability compared with the IS-CPMs although their average torque might be slightly lower due to lower winding factor, which could be compensated by shorter end-winding,