An Analytical Study on Iron Pole Shape Optimization in High-Speed Interior Permanent Magnet Machines

Interior permanent magnet (IPM) motors are of extensive interest in high-speed applications, where high efficiency, high power density and robustness for these motors are a challenge. However, the noise and vibration caused due to cogging torque, electromagnetic torque ripple and reluctance torque ripple can greatly affect the machine performance. The main contribution of this paper is to develop a hyperbolic form analytical expression for optimal rotor iron pole curve in IPM motors to mitigate pulsating torque components. The analytical method is based on the resolution of Laplace equation in air gap sub-domain in polar coordinate by using the sub-domain method. The proposed method is applied to the performance computation of a prototype IPM machine, i.e., a three-phase 18S-8P motor. The analytical results are validated through FEA method and experimental tests.