Iron Loss Analysis of Interior Permanent Magnet Synchronous Motors by Considering Mechanical Stress and Deformation of Stators and Rotors

The iron loss of interior permanent magnet motors driven by inverters are calculated using the combination of stress analysis and electromagnetic field (EMF) analysis for the purpose of taking into account the effect of stress and motor-shape deformation. Both the stator stress caused by shrink fitting and the rotor stress caused by centrifugal force are considered in the stress analysis. In the EMF analysis, harmonic fields, including inverter carrier is taken into account by coupling the finite element equations and the armature voltage equation. The reluctivity and the core-loss coefficient at each finite element are modified according to the stress and flux distributions. In addition, the finite element mesh of the EMF analysis is also deformed according to the motor-shape deformation caused by the centrifugal force. The calculated loss is compared with the experimental loss to confirm the validity of the analysis. Several effects of the stress and the deformation on the iron loss of interior permanent magnet motors driven by inverters are revealed by this analysis.