Fast and accurate non-linear time-domain modeling of synchronous machines

The paper presents a novel method for non-linear 2D magnetic analyses of synchronous electric machines, with the emphasis on permanent magnet and synchronous reluctance AC machines with distributed windings. The foundation of the methodology lies in the air gap magnetic flux being an integral quantity, connecting the two magnetic structures – stator and rotor. The implementation was done through the fixed magnetic permeance configuration. In the method, the rotor and stator sub-models of different complexity were developed, that iteratively exchange the results between each other via the frozen permeability method, until a sufficient accuracy is achieved. Each of the sub-models can have an arbitrary number of nodes for scalar magnetic potentials, in order to accurately describe the magnetic conditions. However, we showed in the paper that only a small number of nodes in both sub-models is sufficient to achieve the accuracy of the results, comparable with the 2D finite element method results. The small number of nodes reflects in the reduced computational efforts of the presented method, giving it a promising forecast for numerous analyses, e.g. for calculations of voltage forms, inductances, armature reaction effects, iron loss estimations, etc. and further, for various optimization procedures.