Design and Comparison of Ferrite Based IPM and NdFeB Based SPM Synchronous Motors for Gearless Elevator Systems

In this paper, gearless elevator systems driven by Interior Permanent Magnet Synchronous Motor (PMSM) is proposed and compared with Surface Mounted PMSM. The IPM motor with ferrite magnet and NdFeB based SPM motor have been comparatively investigated as such different slot/pole combinations and number of flux-barrier layer in IPM motor are analyzed in an effort to reduce torque ripple while minimizing cost and weight. With a parametric optimization process, the torque ripple ratio of IPM motor has been lowered below 5%. In addition due to the use of ferrite, the cost has been reduced by 60% compared to the SPM motor.