Fault Diagnosis and Fault Tolerant Control of a Three-Phase VSI Supplying Sensorless Speed Controlled Induction Motor Drive

Fault diagnosis in variable speed drives under inverter faults has been widely addressed in the literature. However, research activities in this field have been always focused only on sensored motor drives. This paper deals with a mixed model-based and signal-based approach for both insulated-gate bipolar transistor (IGBT) open-circuit fault diagnosis and fault tolerant control in sensorless speed-controlled induction motor (IM) drive. Sliding mode observer (SMO) is used for speed and stator currents estimation and simultaneously open-switch fault diagnosis. Unlike the classical sensored drive systems, this structure presents particular dynamics under faulty operation-mode which can be taken into account for fault detection and identification (FDI) process designing. The proposed diagnostic algorithm is based on similarity test between measured and estimated currents to define the FDI index in the inverter. The proposed method allows detection and localization of single and multiple IGBT open-switch faults. To improve the reliability of the motor drive, the ability of the SMO to reconstitute the motor state estimation after the disturbance stage of the FTC application is verified. The proposed FDI and FTC schemes are implemented on a dSPACE DS1104 controller board for a 3-kW IM drive system. Several experiments are displayed to show the effectiveness and feasibility of the proposed method.