Mitigation of Torque Ripple in Multilayer Interior Permanent Magnet Synchronous Motors by Symmetric and Asymmetric Rotor Core Shaping

This paper presents the impact of rotor core shaping techniques in the U-shaped multilayer rotor structures for interior permanent magnet synchronous motors (IPMSM). Multilayer Rotor topology has been popular for high-speed and high-efficiency applications. However, core losses are higher in multilayer rotor topology during high-speed operation. The rotor core shaping method has been reported in the literature to reduce core losses for V-shaped rotor topology. Inverse cosine function and eccentric rotor core shaping along the d-axis have been proposed. However, the detailed analysis of a rotor core shaping in the multilayer rotor topology along the d-axis still needs to be explored more from a design perspective. Therefore, this paper deals with different core-shaping methods for multilayer U-shaped rotor topology in terms of reduction in torque ripple and core losses and enhancement of average torque. Simulations corresponding to different multilayer rotor topology has been studied through 2D FE simulations and a comparative assessment has been done.