Design And Implementation Of Analog Circuit Fault Simulation And Diagnosis

Following the development of modern science and technology, the integration of the analog circuit has improved significantly, and the circuit is designed more complicated. The topic, how to monitor and diagnosis the state of the circuit effectively, has received considerable attention at home and abroad. To study and develop a practical software, which can monitor the circuit’s state and diagnosis the fault, will help to the design of the analog circuit and the monitor of the system.Although fault dictionary approach is a typical method in the fault diagnosis of the analog circuit, the normal approach is not fit for the fault diagnosis in large-scale analog circuits. The approaches based on multi-signal model are fit for the fault diagnosis of large-scale analog circuits. Therefore, the fault diagnosis method based on multi-signal model is applied to the fault diagnosis in analog circuit.Firstly, the fault dictionary technology and the integrated code fault dictionar technology are studied, and then the method of test point selection based on heuristic graph search is studied too. And the method based on heuristic graph search is used to the monitor of the circuit’s state. In this way, a best test point set and fault dictionary can be found.Secondly, a method that changing the integrated fault dictionary to the fault-test dependence matrix is proposed. According to the method, the fault diagnosis methods based on multi-signal model can be applied to large-scale analog circuit.Finally, a software aiming at simulating and diagnosising the fault in analog circuit is developed. As the fault simulation needs to call the Pspice repeatedly, Pspice auto-simulation platform is developed by the mixed programming of VC++and Pspice in order to reduce the simulation time. And then, test point selection platform which will provide convenience for the later test is integrated to the auto-simulation platform. Meanwhile, three primal fault diagnosis algorithms based on multi-signal model such as real-time diagnosis reasoning, lagrange relaxation algorithm and primal heuristic algorithm are integrated to the fault diagnosis platform, which will provide security for the normal operation of the large-scale analog circuit and system. The experimental result shows that the software can realize the fault simulation, test point selection and fault diagnosis and the result is proved right.