Study On Fault Diagnosis Approach Of Inverter Based On Bond Graph Theory

With the development of semiconductor technology and the upgrading ofpower electronic devices, the AC motor variable frequency speed control system hasbeen widely used in industrial production. At the same time more and more highexpectations and demands for the reliability and safety of the system are proposed. Alarge number of data show that the switches in the inverter is the main reasonleading to the failure of variable frequency speed regulation system. One of the mosteffective methods is to determine the fault location and reason, and isolate the faultcomponents quickly and accurately to ensure the safety of the system when a faultoccurs. Aiming at the nonlinearity and strong coupling of the inverter, the bondgraph model is applied to the fault diagnosis of inverter in this paper, the mainresearch contents are as follows:Firstly, this paper introduces the background and research status at home andabroad of the fault diagnosis methods. The application problems of the existing faultdiagnosis methods are analyzed. Then two fault diagnosis methods using bond graphmodel are proposed.The topological structure and working principle of three-phase voltage inverterare analyzed. A simulation model of the three-phase voltage source inverter isestablished. Focus on the analysis of open-circuit faults and short-circuit faults inthe inverter, we can obtain different output current waveforms through thesimulation. Considering inverters contain both continuous dynamics and discretedynamics, the bond graph model is established, which lays the foundation for thefurther fault diagnosis.In order to overcome the shortcoming of the traditional fault tree analysis, thefault diagnosis method of fault tree is established by using bond graph model. Faulttree is established based on the time causal graph, the simulation results show theeffectiveness of the proposed method. In view of the traditional analyticalredundancy relations can not apply to nonlinear system, a new fault diagnosismethod of analytical redundancy relations using bond graph is proposed. Faults canbe detected and isolated according to the fault residual changes direction. Thesimulation results show that this method is very fast, high accuracy and strongreal-time.