Design of interior PM synchronous traction motor with novel approximate skewed rotor

This paper proposes an alternative solution to reduce torque ripple and high-order harmonics of back electromotive force (EMF) for permanent-magnet synchronous motor (PMSM) design. Inspired by the step-skewed rotor (SSR), this method divides pole shoes into several segments axially and rotates with an appropriate angle circumferentially to structure an approximate skewed rotor. Specially, different with the SSR, the interior magnets are kept coherent axially. In effect, this approach is able to weaken the teeth-slot effects without causing axial flux leakage, which the SSR would cause. In this paper, an interior PM synchronous traction motor will be optimized using the novel method and the remarkable improved electromagnetic performances are confirmed by the finite-element analysis.