Model predictive torque control with duty ratio optimization for two-level inverter-fed induction motor drive

In this paper, an improved model predictive torque control (MPTC) for induction motor (IM) drive is presented. Compared to conventional direct torque control (DTC), MPTC can achieve significant reduced torque and flux ripples by predicting the future system behavior under the limited switching states of inverters. Further steady state performance improvement in MPTC can be obtained by incorporating duty ratio optimization. Namely, the active voltage vector selected from the conventional MPTC will only be applied for a fraction of the control period, while the rest of time is allocated for a null vector. A very simple yet robust and effective method for determination of the duty ratio is employed to improve the performance of MPTC. Presented experimental results prove that the proposed MPTC with duty ratio optimization achieves better steady state performance by reducing torque ripple while maintaining the dynamic performance of the conventional MPTC.