An Improved Analytical Model for Inductance Calculation of Interior Permanent Magnet Machines

This paper proposes an improved analytical model to calculate the inductances of interior permanent magnet (IPM) machines, equipped with either fractional slot concentrated windings or distributed windings. A modified stator magnetic motive force expression is also presented firstly. It has been proven that the normal method for inductance calculation by airgap permeance function and winding function is not accurate enough for IPM machines. The improved analytical model is competent to predict the distribution of the armature-reaction magnetic field and inductances accurately. Several finite element analysis (FEA) models have been built, and a prototype has been designed and tested. Results by the improved analytical model are verified by both FEA and experimental results.