In this study, a new model-based fault detection and isolation (FDI) strategy is proposed for field-oriented control (FOC) induction motor (IM) drives. Actuator faults are addressed, and specifically, single open-circuit faults are considered in this study. The residual signals are synthesised by taking the resulting closed-loop dynamics when a FOC strategy is applied, that is, the residuals are referenced to the synchronous reference frame (dq e-coordinates), which are generated by using a bank of variable structure observers to obtain a robust FDI scheme. Thus, subsystems sensitive to a specific fault, but decoupled from other faults are obtained in a natural way, where only two stator currents and the mechanical position are required for fault isolation purposes. Residual evaluation is carried out in the stator reference frame (dq-coordinates) for the IM model, where the residual direction (angle) is employed to isolate a fault in each one of the six power switches in a voltage source inverter. In addition, the observer FDI scheme can be combined with a fault re-configuration strategy in order to improve the reliability of the motor drive. Experimental results are illustrated for a three-phase 3/4 HP IM drive at different reference frequencies and load torques with single open-circuit faults that verify the ideas presented in this work.
This paper proposes a fault identification system for short and open-circuit switch faults (SOCSF) for a dc/dc converter acting as a Maximum Power Point Tracker (MPPT) in Photovoltaic (PV) systems. A closed-loop operation is assumed for the boost dc/dc converter. A linearizing control plus a Proportional-Derivative (PD) controller is suggested for PV voltage regulation at the maximum power point (MPP). In this study, the SOCSF are modeled by using an additive fault representation and the fault identification (FI) system is synthesized departing from a Luenberger observer. Hence, an FI signal is obtained, which is insensitive to irradiance and load current changes, but affected by the SOCSF. For FI purposes, only the sensors used in the control system are needed. Finally, an experimental evaluation is presented by using a solar array simulator dc power supply and a boost dc/dc converter of 175 W in order to validate the ideas this study exposes.
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