Nonlinear Current Sheet Model of Electrical Machines

An incremental improvement of the classical semi-analytical current sheet model of electrical machines is proposed. First, it provides a better description of the current sheets that allows to consider, 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 current sheet model is particularly suitable for slotless wound rotor machines, being able to represent both the space harmonics and the saturation of the machine with a fair accuracy and computing speed compared to the nonlinear finite element model. Index Terms-Electrical machine modeling and simulation, semi-analytical model, subdomain model, current sheet model, nonlinear material, slotless machine, air cored machine.