In high-performance applications of interior permanent magnet synchronous machines, critical emphasis is laid on torque characteristics of the design, especially average output torque and torque ripple. Consequently, various techniques of rotor step-skewing have been widely proposed and applied to enhance these performance metrics. This paper investigates the effects of conventional and novel pseudo-rotor step-skewing techniques on the torque characteristics of an interior permanent magnet synchronous machine. Using both 2D and 3D finite element analysis, the study provides a comprehensive performance comparison of these two methods. As the results demonstrate, while both techniques achieve significant reductions in torque ripple under normal load conditions with only a marginal decrease in average output torque, their effectiveness is compromised under increased load as a consequence of magnetic saturation. However, the proposed pseudo-step-skewing technique yields a marginal gain in average torque over its conventional counterpart, attributable to the suppression of axial inter-step flux leakage. The findings are experimentally validated, underpinning that the proposed method can be an effective alternative to the conventional one, primarily due to its ease of rotor assembly.
Wang et al. (Tue,) studied this question.