Analysis and Efficient Calculation of the Magnet Eddy Current Loss of PMSM

Accurate evaluation of eddy current losses (ECL) in permanent magnets is crucial for thermal design and operational safety in permanent magnet synchronous machines (PMSMs). In this paper, the composition of magnetic flux harmonics responsible for the ECL is characterized. A spoke-type interior PMSM fractional slot is used as an example to verify the obtained patterns. The influence of current harmonics on the ECL is further evaluated using the finite element method, based on which a simplified prediction model with only two coefficients for the evaluation of ECL in PMSMs is proposed. Finally, an efficient semi-analytical synthesis method based on a limited number of finite element cases has been proposed to consider the impact of high-frequency current harmonics on the ECL. The saturation of the iron core is taken care of by adopting the frozen permeability technique. The comparison of the ECL values and the calculation time under several operation conditions when adopting the conventional time-stepping finite element analysis and the proposed semi-analytical method validate the accuracy of the proposed one. It is shown that the proposed method has the potential to significantly reduce the time needed for the evaluation of ECL considering the influence of current harmonics.