Comprehensive Analysis and Optimized Control of Torque Ripple and Power Factor in a Three-Phase Mutually Coupled Switched Reluctance Motor With Sinusoidal Current Excitation

Abstract

This article presents a comprehensive analysis of torque ripple and power factor for three-phase mutually coupled switched reluctance motors (MCSRMs) with sinusoidal current excitation. MCSRMs controlled by sinusoidal currents have the advantage of using the conventional voltage source inverter and the conventional vector control. However, MCSRMs are characterized by high torque ripple and low power factor. The torque harmonics due to the sinusoidal current excitation are investigated, and the effect of the current excitation angle on the motor saturation level and the power factor is analyzed. These analyses are then used in the development of an optimized control method to reduce torque ripple and to increase power factor and average torque. In the proposed control method, the power factor and phase voltage are calculated by the knowledge of the phase flux linkage and phase current. The phase flux linkage is represented in terms of Fourier coefficients, where these coefficients are functions of direct- and quadrature-axis currents. Hence, they are estimated from 2-D lookup tables (LUTs), which are independent of rotor position. Similarly, the Fourier coefficients of the torque harmonics are also estimated from the 2-D LUTs. The independence of the LUTs from rotor position reduces the size of the LUTs significantly. The proposed control method is validated by experiments on a 2-kW 12/8 MCSRM.