Low Torque Ripple Synchronous Reluctance Machine with Stator Cage Winding

A low torque ripple is of major importance in electrical machines to avoid unwanted secondary effects such as vibration, acoustic noise and wear of mechanical components. This work investigates synchronous reluctance machines using a stator cage winding and the impact of its number of stator bars on the torque ripple. Firstly, the electromagnetic properties of a stator cage winding are discussed. Secondly, the output torque is calculated analytically based on principle of air-gap shear stress. Suitable combinations of number of stator bars and pole pairs are derived to reduce the torque ripple without additional sensitivity analysis or numerical optimization procedures. Finally, finite element analysis for different operating modes, numbers of stator bars and rotor geometries validate the derived results.