Torque Ripple Analysis of Synchronous Reluctance Motor with Different Rotor Topologies for Application with Dimensional Constraint

Synchronous reluctance machine (SynRM) is reemerging as a thermally robust and inexpensive actuator solution mainly due to the lack of permanent magnet. Added to that, the possibilities of having different rotor topologies make it very versatile where further optimization is possible depending on the objective, be it cost, ease of fabrication, power output, or torque quality. In an application where the outer dimension of the motor is strictly limited, this paper compares quantitatively and qualitatively the torque ripple of three SynRM machines of the same stator dimension equipped with different rotor topologies: segmented, tooth and flux barrier. Using an experimentally validated FE model, the torque ripple and the ripple’s harmonic content are compared at maximum load (stator current, IS = 50 A) and load angle (β = π/4). The machine adopting the flux-barrier rotor was shown to have the best torque quality (41% ripple), followed by tooth rotor (78% ripple) and finally segmented rotor (105% ripple). The harmonic contents are also presented and analyzed.