الفهرس 
CHAPTER 1: INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Variable speed AC drives have become a standard for a wide range of industrial applications and processes. Considering these power conversion systems, one of the most important devices is the Voltage Source Inverter (VSI). Although this technology has already achieved a certain level of maturity, due to its complexity and considering that inverters are often exposed to high stresses, unexpected faults may occur, influencing the entire system negatively. Therefore, in order to preclude this harmful influence as well as to improve the system reliability, the development of fault diagnostic methods has gained a lot of interest during the last years. Furthermore, for critical applications where fault-tolerant systems are highly recommended, temporary remedial actions that allow the system to continue operation under faulty conditions are also strongly based on real-time diagnostic algorithms. These can be easily integrated into the drives, helping to improve their reliability and, at the same time, reducing the negative consequences caused by unintentional stoppages. In general, power device failures in the inverter can be broadly classified as open-circuit faults and short-circuit faults. Although the protection against power transistor overcurrent or short-circuit has become a standard feature for industrial drives, open-circuit failures have not yet received so much attention. This kind of failure will not necessarily cause the system to shutdown and can remain undetected for an extended period of time. This may lead to other faults in the converter or in the remaining drive components, resulting in a total system shutdown and high repairing costs. For these reasons, the development of on-line methods that can detect open-circuit faults in VSI-fed AC drives has become an important research field. The main objective of this research work is to present a simple diagnostic and detection method that allows the real-time detection and localization of single and multiple open-circuit faults in the VSI of a three-phase induction motor drive system. Just the motor phase current signals are used for diagnostic faults, so, it does not require the use of extra voltage or any additional sensors, avoiding the subsequent increase of the drive system cost and complexity. Furthermore, the diagnostic algorithm does not require the knowledge of the machine parameters. Also, the performance of the proposed fault diagnostic algorithm under distinct operating conditions (load and speed transients) is investigated. Performance of the proposed diagnostic algorithm, with an indirect Field Oriented Controlled (FOC) induction motor, is verified by simulation and experimental testing. The system modeling on MATLAB/SIMULINK is carried out to evaluate the proposed diagnostic algorithm performance. An experimental system based on a floating point Digital Signal Processor (DSP) is established in the laboratory. Simulation and experimental results are presented to evaluate the accuracy of the proposed diagnostic algorithm. These results show the effectiveness and accuracy of the proposed fault diagnostic algorithm.