Analytical calculation of inductance parameter of tangentially magnetized PM motor based on basic air-gap magnetic field

Because permanent magnets (PMs) exist in the d-axis magnetic circuit of tangentially magnetized PM synchronous motor, its magnetic field and calculation of inductance parameter is different from common synchronous motor. A new analytic method of calculation of PM motor inductance parameter is proposed in this paper, which is based on basic air gap magnetic field and is more convenient than the conventional method using air gap magnetic permeability. The concept of basic air gap magnetic field and how to calculate its magnetic induction are introduced, the analytic calculation procedure of this method is given and the analytic calculation formula is deduced. The inductance parameters of a 350 kW twelve-phase tangential magnetized PM propulsion motor are calculated by the analytic method and Finite Element Method (FEM) and the results have shown that the two cases agree well, so the validity and accuracy of the presented method are verified.