An Embedded Closed-Loop Fault-Tolerant Control Scheme for Nonredundant VSI-Fed Induction Motor Drives

The nonredundant voltage-source inverter, which exploits the possibility of minimum additional components for reconfiguration and operation, is a promising solution to manage faults in one inverter leg. However, control schemes at prefault and postfault conditions are always designed, separately making it hard for control scheme adaptation from normal to fault tolerant. In order to achieve smooth transitions from prefault to postfault, an embeddable fault-tolerant method based on predictive torque control (PTC) is proposed. A generalized voltage vectors, switching command, and cost function accounting for both healthy and faulty conditions are introduced to carry out a general control scheme. A novel fault-diagnosis method based on probability density analysis of the sampling currents is presented for open-circuit fault isolation under PTC scheme. Seamless likely and rapid transient processes from fault occurrence to postfault operation are achieved. Experimental results have demonstrated that the proposed scheme can make power switch fault easily managed by the controller itself.