Rotors for synchronous reluctance traction motors: a comparative study

This paper presents a comparison between two highly salient rotor structures for synchronous reluctance traction motors for electric vehicles. This work is the summary of many years of research aimed at providing an economically advantageous alternative to a currently produced induction motor drive. The traction motor must provide a wide constant power range, high overload capability, low torque ripple and limited temperature rise. For these reasons, the comparison is not limited to torque production and efficiency, but includes torque ripple, noise and temperature rise considerations. The rotors being compared all mate with a common stator structure (also used for the induction motor) but are manufactured with different technologies: it is shown that, although the axially laminated rotor allows higher saliency ratios, the radially laminated (punched) rotor provides better torque uniformity, lower temperature rise with a minor peformance degradation, at a lower manufacturing cost.