Calculation of the flux-linkage characteristics of a switched reluctance motor by flux tube method

The torque developed by a switched reluctance motor (SRM) is dependent on the change of flux-linkage and rotor position. The flux-linkage is a function of both the excitation and the rotor position. Due to the nonlinear nature of this motor, estimation of the flux-linkage characteristics is cumbersome. In this paper, a simple analytical method to estimate the flux-linkage characteristics of SRM is presented. Here, equations for the calculation of inductance and the flux-linkage for three identified regions based on the rotor position; a) fully unaligned to starting of pole overlap, b) starting of pole overlap to full pole overlap, and c) full pole overlap to fully aligned conditions, are derived in terms of motor dimensions, the magnetic properties of the materials used, and the stator excitation. The validation of the results obtained from this new analytical method is carried out using the finite element analysis of the motors.