*Article* **Optimal Rotor Design of Synchronous Reluctance Machines Considering the Effect of Current Angle**

**Hegazy Rezk 1,2,\*, Kotb B. Tawfiq 3,4,5, Peter Sergeant 3,4 and Mohamed N. Ibrahim 3,4,6**


**Abstract:** The torque density and efficiency of synchronous reluctance machines (SynRMs) are greatly affected by the geometry of the rotor. Hence, an optimal design of the SynRM rotor geometry is highly recommended to achieve optimal performance (i.e., torque density, efficiency, and power factor). This paper studies the impact of considering the current angle as a variable during the optimization process on the resulting optimal geometry of the SynRM rotor. Various cases are analyzed and compared for different ranges of current angles during the optimization process. The analysis is carried out using finite element magnetic simulation. The obtained optimal geometry is prototyped for validation purposes. It is observed that when considering the effect of the current angle during the optimization process, the output power of the optimal geometry is about 3.32% higher than that of a fixed current angle case. In addition, during the optimization process, the case which considers the current angle as a variable has reached the optimal rotor geometry faster than that of a fixed current angle case. Moreover, it is observed that for a fixed current angle case, the torque ripple is affected by the selected value of the current angle. The torque ripple is greatly decreased by about 34.20% with a current angle of 45◦ compared to a current angle of 56.50◦, which was introduced in previous literature.

**Keywords:** current angle; design of electric motors; flux-barriers; optimization; synchronous reluctance motor; torque ripple
