Loss analysis of rotor magnet with PWM controller switching frequency variation

When high-power Permanent Magnet Synchronous Motor (PMSM) is operating with large stator current and high rotating speed there will be large amount of harmonics component in stator winding and deduce significant eddy current loss in rotor magnet. A detailed analytical method was proposed which calculated the eddy current loss in rotor magnet based on FFT analysis of stator current. A Finite Element Method (FEM) was founded to evaluate the relation of eddy current loss in rotor magnet and stator winding harmonics which were caused by different switching frequency. The flux densities in air gap, eddy current distribution and eddy current loss in rotor magnet were investigated. At last a testing method was applied to measuring the eddy current loss in rotor magnet which is based on testing descending of back Electromotive Force (EMF), temperature of rotor magnet. The three results have a good agreement with each other.