Characterization and optimization of a permanent magnet synchronous machine

Purpose - The first purpose of this paper is to identify by an inverse problem the unknown material characteristics in a permanent magnet synchronous machine in order to obtain a numerical model that is a realistic representation of the machine. The second purpose is to optimize the machine geometrically using the accurate numerical model for a maximal torque to losses ratio. Using the optimized geometry, a new machine can be manufactured that is more efficient than the original. Design/methodology/approach - A 2D finite element model of the machine is built, using a nonlinear material characteristic that contains three parameters. The parameters are identified by an inverse problem, starting from torque measurements. The validation is based on local BH measurements on the stator iron. Findings - Geometrical parameters of the motor are optimized at small load (low-stator currents) and at full load (high-stator currents). If the optimization is carried out for a small load, the stator teeth are chosen wider in order to reduce iron loss. An optimization at full load results in a larger copper section so that the copper loss is reduced. Research limitations/implications - The identification of the material parameters is influenced by the tolerance on the air gap shown by a sensitivity analysis in the paper and by 3D effects, which are not taken into account in the 2D model. Practical implications - The identification of the material parameters guarantees that the numerical model describes the real material properties in the machine, which may be different from the properties given by the manufacturer because of mechanical stress and material degradation. Originality/value - The optimization is more accurate because the material properties, used in the numerical model, are determined by the solution of an inverse problem that uses measurements on the machine