Exploring Multilevel Hysteresis Torque Band Direct Torque Control in Switched Reluctance Motor Drives: Insights Into Three and Four-Phase Systems

Due to their robust rotor structure and fault-tolerance characteristics, switched reluctance motors (SRMs) are the choice of next-generation electric vehicle (EVs) traction motor applications. However, this SRM drive suffers from high torque ripples, which may cause severe vibration and acoustics. The existing SRM-operated Direct Torque Control (DTC), utilizing 8 Voltage Vectors (VV s), induces high torque ripples due to minimal switching state selection and improper sector partitioning. Conversely, a two-level hysteresis torque band can exacerbate torque ripples. Therefore, the current DTC methodology in VV selection leads to pronounced torque ripples in SRM. This paper proposes a DTC approach employing active small and large VV s, alongside a multilevel hysteresis torque band strategy, to alleviate torque ripple in three and four-phase SRM drives. Incorporating additional active VVs (i.e., 8, 16) within modified sector-based switching tables effectively suppresses torque ripples. The proposed strategy is validated using MA TLAB/Simulink, with detailed results discussing the response of torque, flux, and speed of SRM. Experimental results from the DTC-MHTB operation in three and four-phase SRM drives substantiate the effective minimization of torque ripples.