Torque calculation of five-phase synchronous reluctance motors with shifted-asymmetrical-salient-poles under saturation condition

Abstract

In traditional analytical method (AM), the magnetic saturation is always ignored to simplify the calculation process. However, synchronous reluctance motors (SynRMs) often operate around saturation point to achieve higher torque density. Therefore, a new AM is proposed, in which the saturation of stator iron has been considered. The key of the proposed method includes a saturation factor, and an iterative method is adopted to compute the saturation factor in the SynRM by increasing the air-gap length. Especially, the proposed AM can be applied to a SynRM even with shifted-asymmetrical-salient-poles. In the process of AM, the expression of stator magnetomotive force (MMF) is built firstly. Additionally, the air-gap density including slotting effect and salient-poles is calculated. Then, the rotor MMF under saturation of the stator iron is obtained. Therefore, the precision of the instantaneous torque can be improved significantly. Eventually, by the verification of finite elements method (FEM) and experiments, the torque performance of SynRMs with shifted asymmetrical rotor can be predicted accurately by the proposed AM.