Nonlinear mathematical modeling and simulation of Switched Reluctance Motor

This paper presents the analytical Modeling of Switched Reluctance Motor(SRM) based on the data obtained from Finite Element Analysis(FEA) tool Ansys Maxwell. Once the design of the machine is done in FEA tool then before manufacturing the actual machine it is necessary to test its dynamic performance. Testing of dynamic performance involves the operation of the motor with different control strategy for various loading and speed condition. Use of FEA model in such a testing takes a lot of time so it is time-consuming in the development of the machine. So analytical model which approximates the FEA model while preserving the accuracy of the system is necessary to reduce development time. This paper derives the non-linear mathematical model of 7.5kW, 8/6 SRM. This modeling is based on an approximation of phase self-inductance using Fourier Series (FS) approach with the help of data obtained from FEA tool. The dependence of phase self inductance on rotor position is incorporated in the developed mathematical model using FS terms and coefficients of series are taken as a polynomial function of current to account for the nonlinear variation of inductance with respect to current. To improve the accuracy of model five FS terms are used instead of three. Polynomial fit used for approximation of inductance variation as a function of current is split into two polynomial equations to accommodate the wide variation of inductance with a current. This mathematical model is developed in MATLAB-Simulink environment and hysteresis controller is designed to control the current flowing through the winding of machine. For validation of MATLAB model static and dynamic inductance profile, dynamic torque, flux, and phase current obtained from the model are compared with simulation done in FEA tool.