An improved diagnosis technique for IGBTs open-circuit fault in PWM-VSI-fed induction motor drive

This paper deals with an improved technique for insulated-gate bipolar transistors (IGBTs) open-circuit fault diagnoses in voltage source inverter (VSI) fed induction motors. The extraction of the fault information is based on the combining of the switching pattern and the electric drive line-to-line voltage measurements. The combined diagnosis signals make possible to detect and identify the single and multiple open-circuit faults of the inverter switches. Furthermore, only one line-to-line voltage is necessary to diagnose two inverter legs simultaneously. For simplicity and cost-effectiveness, the fault detection is carried out by a simple circuit. To avoid the false diagnosis alarms, the time delays due to turn-on and turn-off process of the power switches are compensated while acting on the switching pattern. Different from the conventional method, the proposed technique was marked by a better time delay between the fault occurrence and its detection. The Simulation results are displayed to confirm the proposal.