Predictive torque and flux control of a four-switch inverter-fed IM drive

This paper presents torque and flux control of induction motor (IM) drive fed by a four-switch three phase inverter (FSTPI). Finite-state model predictive control (FS-MPC) strategy is used to select the switching states of the inverter. The proposed controller reduces cost of the inverter, the switching losses, and the prediction time of the control algorithm as compared with conventional six-switch three phase inverter (FSTPI) based two-level voltage source inverter (VSI). Since modern digital signal processors (DSPs) support high sampling frequency, FS-MPC based FSTPI produces almost balanced stator phase currents. This paper also proposes a least square based normalized cost function giving priority on stator flux in relation to the torque. The effectiveness of the proposed cost function is compared with the conventional normalized and ranking based cost functions. Simulation results on steady state and dynamic operation have revealed that, FSTPI fed IM drive exhibits good torque and flux behavior.