Analytical Prediction of Nonuniform Current Profiles of Switched Reluctance Machines

An analytical method (AM) is developed to predict the phase current profiles of switched reluctance machines (SRMs). The field modulation theory and winding functions are employed to predict the main air-gap fluxes, whilst the slot leakage fluxes are included via a simplified magnetic network model. The saturation coefficients are introduced to account for the magnetic saturation and phase coupling. Moreover, the voltage equations and current expressions of SRMs are analytically derived considering the asymmetric half-bridge circuit, based on which the instantaneous torque is calculated with the Lorentz force law. Based on the developed AM, the current profiles of the SRMs are analytically predicted under either angle position control or current chopping control, with flexible control parameters. As a result, the corresponding torque output with the practical currents can be analytically predicted, and the maximum torque per ampere (MTPA) current angles are identified. The AM-predicted results are comprehensively validated by the finite element method. A 12-stator-slot/8-rotor-pole SRM prototype is manufactured, with which the accuracy and reliability of the AM are experimentally verified.