Review of Harmonic Suppression Methods for Fractional Slot Concentrated Winding Permanent Magnet Machines Based on Structural Optimization

The high standards of motor performance demand have driven the rapid development of fractional-slot concentrated winding permanent magnet synchronous motors(FSCWPMSM) in fields such as industrial automation, green energy systems, and future transportation technologies. However, the suppression of low-order harmonics has become the main obstacle to further improving their performance, leading to a series of issues such as increased torque ripple and noise vibration, and reduced output torque, which in turn affect the overall performance of the motor. To address this issue, harmonic suppression methods for FSCWPMSM based on structural optimization are explored, categorizing and summarizing the structural design schemes of recent years from three dimensions: rotor, stator, and air gap, such as combinations of permanent magnet materials, modularization of the stator, multi-layer winding structures, and unequal number of turns per coil winding. These methods systematically analyze the impact of different schemes on indicators such as magnetic motive force harmonics, electromotive force harmonics, load air gap flux density harmonics, and slot torque. Finally, the advantages and limitations of existing design methods are summarized, and future research directions for the remaining harmonic suppression issues are discussed and prospected from different perspectives.