Torque ripple reduction of model predictive torque control of induction motor drives

Model predictive torque control (MPTC) has been proposed as an effective alternative to conventional direct torque control (DTC) for induction motor (IM) drives. Compared to DTC, MPTC is more effective and accurate in the vector selection by incorporating the system model directly with the finite switching states. However, due to the limited switching states in two-level inverter, applying only one voltage vector during one control period fails to reduce the torque ripple to the minimum value. This paper proposes an improved MPTC for the aim of torque ripple reduction by allocating only a fraction of control period to the active vector selected from conventional MPTC, while the rest of time is allocated for a null vector. The duration of the active vector is obtained based on the principle of torque ripple minimization. Presented simulation and experimental results prove that, compared to conventional MPTC, the proposed MPTC achieves better steady state performance by reducing both torque ripples and current harmonics. Meanwhile, the quick dynamic response of conventional MPTC is reserved.