Research On Intelligent Fault Diagnosis And Its Application In Inverter

At present, the fault diagnosis technology of the ac transmission system is widely concerned, and the research on diagnosis is focusing on the inverter's fault diagnosis after the reliability of the motor is solved. The fault diagnosis has entered the phase of intelligent diagnosis. The intelligent fault diagnosis methods have been paid much attention because they don't need the math model of the object. However, in terms of the various intelligent methods which have been developed at present, there are limitations,so the technology of integrating multiple intelligent diagnosis has become a hotspot..In this article, on the basis of studying about the theory of intelligent fault diagnosis,two methods of integrated intelligent fault diagnosis were proposed, one was the integration of FTA and BAM, the other one was based on the BP network and D-S evidence theory, specificly, those two intelligent methods were applied to the inverter and the inverter's most vulnerable part -the inverter circuit. Based on the study about the application of FTA and BAM network in fault diagnosis, a method of fault diagnosis based on the fuse of FTA and BAM was proposed. All of the fault modes were obtained by FTA, then the learning sample ofBAM were summarized which were the corresponding relations between the fault sign(the status of the monitoring points)and the happening or not of the bottom events in fault tree. The results of diagnosis were associated parallel by the associative memory matrix, thus expanding the general ability of fault diagnosis. An emulation of the realization of fault diagnosis with the method mentioned above was performed, and analytical results showed that the approach is valid to fault diagnosis.According to the characteristics of BP network and D-S evidence theory, a diagnosis model combined the advantages of BP and D-S theory was constructed. Each measuring point established its sub-BP network, finishing partial diagnosis of single measuring point. Then the credibility functions of D-S were constructed by using each BP's partial diagnosis result, completing the fusion of multiple evidence information. Finally, the comprehensive diagnosis results were got. The feasibility and effectiveness of this method was verified by the simulation analysis of fault diagnosis in inverter's key components-the inverter circuit.