Improved direct torque control on an induction machine with short circuit fault

Direct torque control (DTC) is one of the most widely used vector controls to improve the transient behavior of electrical and mechanical quantities in induction machines (IM). The inter-turn short circuit (ITSC) fault is one of the most common faults in this type of machines; this fault significantly degrades the expected performance of the DTC. For a certain short circuit rate, this type of control cannot be launched and therefore a diagnosis at zero speed is required before launching the control. In this paper, we propose the simulation of the behavior of the DTC of an IM when an ITSC fault appears. The simulation of this type of converter-machine association has given very interesting results in terms of stability, accuracy and the ripple of the mechanical quantities torque and speed. This paper presents an interesting possibility to improve the behavior of the DTC for a tolerable short-circuit rate less than 15%. For this value, the new performances of this controller-machine association show a significant improvement in stability (from unstable to stable), in speed ripple (from unstable to 1.17%) and in torque ripple (from unstable to 170%).