Analysis and Suppression on Torque Ripple of Interior Permanent-Magnet Machine by Using Rotor Modification

Background Torque ripple in Interior Permanent-Magnet (IPM) Machines is influenced by the spatial harmonic components of the air-gap flux density and related magnetic field harmonics, which limit its performance gains. An effective solution through rotor structure optimization is urgently required. Objective This study introduces a new rotor topology suitable for IPM Machines. The goal is to suppress spatial harmonics of air-gap flux density and magnetic field harmonics through structural improvements, thereby effectively reducing torque ripple. Methods Design appropriate flux barriers with triangular slots to alter the leakage flux path and inhibit harmonic components. Derive the torque ripple generation mechanism of IPM machines and develop a mathematical model that reveals the relationship between rotor modification and torque ripple. Optimize the design of an 18-slot, 8-pole IPM machine and compare it with the existing design. Analyze key performance metrics including air-gap flux density, no-load back-EMF, and torque ripple using finite-element method (FEM). Results FEM analysis results show that the proposed rotor topology can significantly decrease the spatial harmonic components of the air-gap flux density and suppress the magnetic field harmonics associated with torque ripple, achieving a notable torque ripple reduction. Conclusions The proposed new rotor topology is well-designed and effective. It offers a dependable solution for reducing torque ripple in IPM Machines and has practical reference value for optimizing their performance.