Nonlinear Current Sheet Model of Electrical Machines

An incremental improvement of the classical semi-analytical current sheet (CS) model of electrical machines is proposed. First, it provides a better description of the CSs that allows considering, at the same time, the rotation of the rotor field winding and the time-dependent stator armature windings currents. This derivation is kept generic, and the system to be solved is explicitly written in order to facilitate the implementation. Second, a refined iterative scheme that permits to account effectively for the nonlinearity of iron cores is introduced. It is demonstrated that the nonlinear CS model is particularly suitable for slotless wound rotor machines, being able to represent both space harmonics and saturation of the machine with a fair accuracy and computing speed compared with the nonlinear finite-element model.