Abstract: Magnetic saturation, field harmonics distortion and changes of magnetic energy storage will cause conventional model distort in heavy load condition of PMSM. The magnetic energy storage change effect is considered and reformed formula of counter electromotive force and torque of PMSM is introduced. A given motor is  electromagnetically analyzed using finite element software Ansys EM and cross saturation inductance curves, demagnetization curves and harmonic parameter are extracted. A nonlinear d-q axis motor model is established and tested on Matlab simulation platform based on extracted parameters. Result shows that the reformed model can reflect the electromagnetic torque harmonics of the PMSM much more accurately than the conventional one. Therefore a more accurate PMSM model basis is designed and tested for characteristics of PMSM drive research in heavy load.

Key words: PMSM, field harmonics, magnetic saturation, magnetic energy storage, electromagnetic torque harmonics