Browsing by Author "AMIR RASYADAN BIN KELANA"

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    FAULT DETECTION AND LOCALIZATION METHOD FOR INVERTER OPEN-CIRCUIT CONDITION IN THREE-PHASE INDUCTION MOTOR DRIVES
    (2019) AMIR RASYADAN BIN KELANA
    Recent advancement in semiconductor technologies have extended the use of induction motors in a wide area of variable speed applications. Traditional fixed speed drives are becoming obsolete and majority of the applications now require power electronic inverter-based drives for a more efficient and precise speed control. Nonetheless, the use of power electronic came with an increased possibility of the drive system failure, mainly caused by the switching device itself. There are two common types of inverter faults which are short-circuit and open-circuit fault. Short-circuit fault detection methods are mostly hardware based while open-circuit faults require proper algorithm to be detected. The aim of this research work is to provide a simulation analysis on the inverter fault detection algorithm to detect open-circuit fault together with fault localization algorithm to locate the open-circuit switch in a three-phase induction motor drive. Computer simulation model was built using MATLAB Simulink to simulate the operation of three-phase induction motor drive under healthy and faulty inverter conditions. The sub models of the drive system include an induction motor direct-quadrature (DQ) model, a voltage source inverter (VSI) driven by an open-loop SPWM and a graphical user interface (GUI) to allow user control on the input parameters during simulation run. Dynamic behavior of the motor speed, phase current and electromagnetic torque under healthy and the combinations of single and double open-circuit fault conditions were simulated. The simulated phase currents were then pre-processed to filter the signal from multiple harmonic content induced by the PWM-switching process before being used for features extraction. This work focuses on current vector trajectory based fault detection and localization (FDL) method, two separate algorithms are used to detect the faulty inverter leg and to localize the faulty switch within the faulty leg. Fault detection was done using the modified slope calculation method of the phase currents in the complex DQ plane, while the xx localization strategy is based on the observation of the phase currents polarity. 21 combinations of single and double open-circuit faults were simulated. The results have shown that the FDL method is capable to detect and localize all the 21 fault conditions. Since the fault pattern may appear at different current angle, the detection and localization speed depend on the fault occurrence angle which varies within one phase current period. The algorithm also proved to work under variable load and frequency conditions. Overall, this work has shown the working principle and the capability of the current vector trajectory based FDL algorithm to detect and to localize the 21 open-circuit fault conditions. The simulation analysis done in this work would be useful for future development of the FDL algorithm.