Advanced Band-Constrained Direct Torque Control Strategy for SPMSM Drive for Torque and Flux Ripple Reduction

Band-constrained direct torque control (BC-DTC) of surface-mounted permanent magnet synchronous motors (SPMSMs) is known to maintain the simple control implementation of the conventional DTC with better steady-state torque performance at a relatively low sampling frequency. However, it lacks the theoretical basis for setting the hysteresis band limit that ensures selecting the proper voltage vector under different operating conditions. Also, this selection does not consider the flux control behavior, leading to high stator flux ripple and current distortions. To overcome these issues, this paper presents an advanced BC-DTC strategy with adjustable band limits and adaptive voltage vector selection. The proposed strategy optimizes the switching instant not only to restrict the torque within the hysteresis bounds but also to minimize the torque ripple without increasing the sampling frequency. Experimental evaluations for the proposed and conventional solutions verify the considerable reductions in torque ripple, stator flux ripple, and current distortion.