On-Line Fault Diagnosis For High-Power Power Electronics Equipment

On-line fault diagnosis for high-power power electronics equipments is a significative subject. It is an intersectional subject that has been come into being in order to adapt to the engineering demand. Lately, overseas and local scholars have done much research on this field and great results have been obtained. However, much improvement should be done on the diagnosis method and realized means. For this reason, theories analysis and experiment research on high-power power electronics equipments are carried out in this thesis.The developing situation of fault diagnosis is introduced firstly, then the research purpose and meaning of this thesis are summarized, and the recent research condition and characteristics of the fault diagnosis for high-power power electronics equipments are analyzed. Then, the scheme of this thesis is established, primarily includes the theories analysis and realized means two aspects. In theory analysis, the voltage waveforms of the 12-pulse waveform controlled rectifier circuit and three-phase thyristor converter under fault and normal condition are analyzed and researched in detail, all the faults states are summarized and classified according to the aberrant voltage waveforms. An improved spectrum frequency analysis fault diagnosis method is put forward with the logic pre-processing and spectrum analysis of the fault voltage waveforms. The experiment algorithm of the diagnosis system is induced, and the characteristic of this method is summarized. Furthermore, fault diagnosis method for controlled rectifier circuit based on neural network is explored.In the realizing aspect, TMS320 LF2407A is used as core control chip and the faultdiagnosis system for controlled rectifier circuit based on DSP is developed. The fault diagnosis system includes four parts: sampling and insulation of the synchronous signal, sampling of the voltage waveform of the rectifier, logic pre-processing and DFT analysis, display and alarm circuit. Software includes designing of the DSP initialization files, sampling and processing program of the synchronous signal , sampling and logic pre-processing program of the rectifier voltage, program of fault diagnosis and location, display and alarm program, delay and ISR program.Finally, experiments are carried out with the developed DSP on-line fault diagnosis system. During the experiment, all the mentioned fault states are simulated. That shows the system can detect and locate the faults quickly and exactly by using the proposed method. It can inspect and diagnose the faults on-line.