Minimizing torque ripple for switched reluctance motor through optimum torque sharing function

Abstract

Switched Reluctance Motor (SRM) is emerging as an alternative to traditional drives because of its advantages such as lightweight, robust structure and fault-tolerant nature. SRM has been proposed for various sectors in domestic and industrial applications. However, torque ripple stands as a prominent challenge in SRM. The double-salient geometry introduces a significant ripple in its torque profile, leading to vibration and acoustic noise. SRM needs continuous position information and a sequential switching approach, unlike traditional motor drives. Torque Sharing Function (TSF) is a widely used torque control scheme for SRM. In TSF, the commutation ripple is controlled by adjusting the conduction period of incoming and outgoing phases. This article presents a novel TSF with conduction angle control. The linear and cubic TSFs are combined to create a hybrid TSF, and conduction angles are optimized to reduce the ripple up to a speed of 2000 rpm in a 1 hp SRM. A PI controller works as the outer loop torque controller, and hysteresis band current control is implemented for the inner loop current control. Simulation results show that the optimal conduction angle reduced the torque ripple from 125% to 20%. Further, with the proposed novel hybrid TSF, it has been reduced up to 2.70%.