Design and analysis of an axial flux dual stator flux modulating synchronous reluctance machine

This paper presents an axial flux dual stator flux modulating synchronous machine, referred to here as axial flux modulating synchronous machine (AFMSM) for simplicity. The proposed machine has dual stators with a non-overlapped concentrated armature winding on the upper stator and field winding on the lower stator. The recently developed radial flux modulation synchronous machine (RFMSM) employs both field winding and armature winding on a single stator. Due to separate winding on different stators in the proposed AFMSM, the armature winding has more freedom of fill factor compared to single stator RFMSM. The surface current density of the proposed machine can also be doubled compared to the RFMSM due to individual winding on separate stators. Moreover, due to dual stator and axial flux topology, the rotor does not need back iron and the torque to volume ratio of the machine is rather better than single stator radial flux machine. The electromagnetic characteristics of the proposed machine are investigated using 3D finite element analysis (FEA). Two types of rotor pole shapes i.e. general shape and sinusoidal shape have been studied to improve the cogging torque and torque ripple. The performance with both kind of rotor pole shapes have been compared. The variable speed characteristics of the machine are investigated, and it is observed that the speed of the machine can be increased by adjusting the field current.