Analytically computing the flux linked by a switched reluctance motor phase when the stator and rotor poles overlap

This paper develops an analytical model for the flux linked by a phase of a switched reluctance motor (SRM) starting with the basic laws for magnetic fields. Thus this model is not empirical nor does it require any data from the machine being modeled or any finite-element analysis results. The model is applicable to rotor positions where the stator and rotor poles overlap, and it includes iron saturation. This paper gives a detailed development of the analytical model including the approximations that are inherent to it and the justification for them. The analytical model for the flux linked by a phase is used to find the analytical equations of motion for the SRM. It is also used to obtain an analytical expression for the SRM's coenergy. Differentiating the coenergy with respect to rotor position, holding the current constant gives an analytical expression for the torque. Finally, this paper compares the analytical model's predictions to measured data from experimental machines.