Direct Instantaneous Torque Control for Switched Reluctance Motor through Optimized Dwell Angle

Abstract

Switched Reluctance Motor (SRM) is emerging as a reliable motor in many industrial applications. There has been an emerging adoption of SRM in electric vehicles, hybrid electric vehicles, turbochargers, turbo-compounding, household, and aerospace applications. The control mechanism for SRM is complicated because of its highly non-linear characteristics. Because of the salient structure, there is a non-uniformity in the air gap, which lead to issues like torque ripple and noise and vibration in SRM. The torque ripple comprises the current hysteresis and commutation between phases while operating at low speeds. Whereas during high-speed operation, the single pulse current profile degrades the quality of the torque. In indirect torque control, the torque is indirectly controlled by considering current as a control variable, thereby increasing the computational burden. Direct torque control techniques, which directly use torque as a control variable, are attracting attention from researchers. This work presents a novel Direct Instantaneous Torque Control (DITC) method that considers the dwell angle optimization and its effect on the torque ripple. Further comparison of the proposed DITC model with the conventional current control is performed. A 5 kW, 1500 rpm, 8/6, 4-phase SRM is modelled, and the current control is carried out using the MATLAB model; hysteresis control is performed at low operating speed and single pulse control at high speeds. To achieve the minimized torque ripple, the conduction angle is optimized using ANSYS MAXWELL. The DITC method is then implemented using the optimized conduction angles. Finally, the comparisons of steady-state torque ripple and the current waveform are presented. The proposed DITC model performs dramatic torque ripple reduction compared to conventional control.