Accurate Calculation of Iron Loss Based on Frequency Division and Piecewise Variable Coefficient for Magnetic Field Modulation Permanent Magnet Machine

The Magnetic Field Modulation Permanent Magnet Machine (MFMPMM) is commonly employed in low speed and high torque applications, however, its rich modulation harmonics bring challenges for the traditional loss calculation model to achieve accurate core loss estimations. In order to address this issue, a frequency division and piecewise variable coefficient iron loss calculation model is established and studied in this paper. On the one hand, considering the influence of nonlinear enhancement and magnetic saturation on the loss calculation, the hysteresis loss (HL) and the eddy current loss (ECL) additional terms are introduced. On the other hand, the frequency and magnetic flux density are segmented, and the hysteresis and eddy current losses are compensated by fitting coefficients of the additional terms in each magnetic flux density or frequency segment. To validate the reliability of this model, the three-dimensional finite element model of the MFMPMM is established by Maxwell software. And then, the feature points of magnetic flux density are selected for analysis. Furthermore, the calculation results obtained from the proposed calculation model, the Bertotti loss separation model, and the finite element analysis (FEA) are compared and analyzed. Finally, a loss test platform is set up to further verify the accuracy of the proposed iron loss calculation method. The findings demonstrate that the model exhibits higher precision.