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

Due to the existence of rich modulation harmonics in magnetic field modulation permanent magnet machine (MFMPMM), the traditional Bertotti loss separation model is disable to satisfy the calculating accuracy of the iron core loss. With a view of improving the calculation accuracy, a frequency division and piecewise variable coefficient iron loss calculation model is established and studied in this paper. First, in the low frequency band, the loss coefficient is calculated and fitted in accordance with the smaller frequency and magnetic flux density; in the high frequency band, considering the impact of core nonlinear enhancement and magnetic saturation on iron loss, the additional magnetic flux density low-order term and high-order term are introduced to compensate the hysteresis loss and eddy current loss, meanwhile, the magnetic flux density and frequency are segmented, and the hysteresis and eddy current loss are compensated by fitting different compensation item coefficients in each segment interval. Then, the three-dimensional model of MFMPMM is established by Maxwell software, and the precision of the researched model is verified by comparing the results of the frequency division and piecewise variable coefficient model, the Bertotti model and the finite element analysis (FEA). Finally, the validity of the researched iron loss calculation model is further verified by the no-load loss test, and the result shows that the calculation value of the researched model is close to the measured value.