Rotor design and optimizations for interior permanent magnet machines in motorized spindle application

For the motorized spindle applications, the interior permanent magnet (IPM) machines is preferred to be chosen than surface mounted permanent magnet (SPM) machines, since it has better magnet protection ability, easier magnet installation, and less magnet loss. However, IPM machines usually has higher stator core loss, higher torque ripple, etc. Especially, when the machine is working under over loading condition. In this paper, some different structures of rotor design are analyzed on flux density, core loss, magnet loss, torque ripple and so on. Furthermore, the optimizations of those structures have been done to obtain better design which is suitable for motorized spindle application. As a result, compared to the traditional V-type IPM machine, through suitable rotor design and optimization, the stator core loss could be reduced about 20%, and torque ripple could be reduced from 30% to less than 10% without the slot skewing or some others methods.