Precise Prediction of Air-Gap Magnetic Harmonics for IPMSM Based on Improved Magnetic Field Modulation Theory

The interior permanent magnet synchronous machine (IPMSM) provides remarkable advantages including high power density, superior efficiency, and broad speed range, rendering it a prevalent choice in the electric vehicle drive domain. However, owing to its complicated structure, the analysis of IPMSM proves challenging. The traditional magnetic field modulation theory employs the three-element method to standardize the principle analysis and calculation across various types of motors. However, the quantitative calculation is not highly accurate. This article presents an improved magnetic field modulation method for air gap magnetic field analysis to solve the issue of inaccurate prediction of magnetic flux density in air gaps by traditional magnetic field modulation theory. The equivalent magnetic circuit (EMC) method is employed to establish a precise permeance model for the IPMSM, hence, an accurate prediction of air-gap flux density is calculated by the model.