| Summary: | 碩士 === 國立勤益科技大學 === 電機工程系 === 105 === This thesis presents an extension theory-based assessing method to apply fault diagnosis for inverters in motor driving systems. First, a three-level neutral point clamped (NPC) inverter was created using the PSIM software to simulate faults occurring on any power transistor in the NPC-type inverter. Also, Fast Fourier Transform was used to transform line current signals in time domain into spectrum in frequency domain for analysis of the corresponding spectrum of feature of the inverter in case of faults of different power transistors. Then, the relationship between the fault types and specific spectra was established as characteristics for extension assessment method, whereby to further create a smart fault diagnosis system for inverters. Fault-tolerant control (FTC) was further used, in the event of faulty inverter with its rated output decreased, to maintain output in balanced three phases by changing the framework of transistor connection, to reinforce the reliability of the inverter. Finally, by the results of simulation and experiment, the feasibility of the proposed smart fault diagnosis system was testified. The proposed fault diagnosing method features the advantages of minimum data, requiring no learning process, due to which fault diagnosing time is reduced, and being easy to realize. The proposed fault tolerant control strategy allows online and smooth switching in the wiring structure of the inverter.
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