Fault-Tolerant Predictive Torque Control Design for Induction Motor Drives Based on Discrete Space Vector Modulation

Four-switch three-phase inverters (FSTPIs) are generally applied as fault-tolerant topologies or cost-effective topologies for induction motor (IM) drives. However, conventional predictive torque control (PTC) for FSTPI-fed IM suffers from poor steady-state performance and tedious weighting factor assignment. In this article, a PTC based on discrete space vector modulation (PTC-DSVM) for an FSTPI-fed IM drive is proposed. First, the relationship between the dc-link capacitor voltage offset (CVO) and the load current is derived, and a stator voltage compensation strategy is proposed to suppress the CVO. Meanwhile, a reference-voltage-vector-error-based cost function that combines the reference stator flux vector control, the stator voltage compensation strategy, and the deadbeat control is designed to fully eliminate the weighting factors in the cost function of the conventional PTC. In addition, a DSVM scheme is developed to increase the number of admissible voltage vectors and improve the steady-state performance of IM drives. A preselection algorithm based on the offset voltage vector and sector division is designed to reduce the number of candidate voltage vectors. Extensive simulations and experimental results with a 2.2-kW IM are demonstrated to validate the effectiveness of the proposed control strategy.