Analysis of the iron loss of line start permanent magnet synchronous motor using time-stepping finite element method

This paper deals with investigation on iron loss analysis of line-start permanent synchronous motor (PMSM), which is applied in some industrial field and its load condition and voltage changes frequently. Time-stepping finite element method (T-S FEM) is employed to calculate the loss density in iron-core of PMSM with considering the harmonics of the flux density, and the total iron loss can be obtained by the summation of the iron losses in all the elements. The spatial discretization density, which affects loss calculation because the losses in the iron-core distribute non-uniformity, is investigated in this paper. Moreover there is such high frequency harmonic field in the rotor core caused by slot harmonic, to avoid folding phenomenon take place in calculation, this paper also investigates the related problem of time discretization, thus to ensure the computing precision. By represent the flux density as a Fourier series and calculate the series components of eddy current loss caused by harmonic field, the main component of eddy current loss and its variation under different operation conditions are obtained, the result indicate that there is a significant influence of slot harmonic field to iron loss. Finally the predictions of iron loss are compared with measurements.