Multiphysics Design of Triple 3-Phase PMSM for Ultra-High Speed Elevator Applications

This paper proposes triple three-phase surface-mounted permanent magnet synchronous machine (PMSM) as a fascinating solution for ultra-high speed (1260m/min) elevator direct-drive applications and describes its multiphysics design procedure. Particularly, the design procedure focused not only on achieving the required output power, but also on decreasing the low frequency radial vibration and the torque pulsation to ameliorate the riding comfort of occupants. As a result, the 144-slot and 40-pole combination with 20 electrical degree of phase shift was chosen considering the following criteria: winding factor, frequency and space order of radial force, cogging torque, and optimal phase shift between adjacent sets. In addition, the rotor diameter was rearranged to enhance power factor and efficiency. The robust design optimization was also carried out to ensure the manufacturing uncertainties. As a result, an optimum model was obtained and analyzed through FEA in order to justify the aforementioned design procedure. Finally, it was compared with the 144-slot and 32-pole prototype to validate its effectiveness.