Enhanced Direct Torque Control of SRM Based on a Novel Multilevel Hysteresis Torque Band With Effective Voltage Vectors for Low Torque Ripple
M. Deepak, C. Bharatiraja, Sheldon S. Williamson, Mahesh Krishnamurthy
Abstract
Due to their robust rotor structure and fault-tolerance characteristics, switching 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) using 8 Voltage vectors (VVs) gives high torque ripples due to the minimum selection of switching states and improper sector partition. On the other hand, a two-level hysteresis torque band can result in torque ripples. Therefore, existing DTC for selecting VVs produces high torque ripples in SRM. This paper proposed DTC using active small and large VVs and a multilevel hysteresis torque band (MHTB) strategy to mitigate the torque ripple further. The selection of VVs and sectors is organized in the optimal values for the three and four phases. More active VVs (i.e., 16) are employed in the modified sector-based switching tables, suppressing the torque ripples. The proposed strategy is verified and validated using MATLAB/Simulink. The detailed result discusses the response of torque, flux, and speed of SRM. The DTC-operated SRM drive experimental results are shown to prove the effective minimization of torque ripples in the proposed DTC compared to the existing DTC.