A sliding mode observer for inverter open-switch fault diagnostic in sensorless induction motor drive

Abstract

This paper deals with a simple, robust and real-time technique for single and simultaneous insulated gate bipolar transistor (IGBT) open circuit fault diagnostic in sensorless vector controlled induction motor (IM) drives. A full sliding mode observer (SMO) is used for speed, flux and stator currents estimation and simultaneously open switch fault diagnostic. The proposed open switch fault detection and identification method requires just the measured three phase currents. However, there is no extra sensors used by the proposed technique. The main idea consists in comparing of similarity between the measured and the observed current of each phase. Threshold are defined and used to detect the fault occurrence in the voltage source inverter (VSI). The effectiveness and robustness of the proposed algorithm are justified based on extensive experimental tests on 3-kW induction motor.