| Circuits tolerance analysis covers subjects of circuits analysis,computational mathematics,digital simulation,physics of failure etc. It is a key technology to enhance the reliability of circuits. Based the background of reliability technology study on one certain type of power conditioning system of ICF,this paper will keen on circuit tolerance analysis problems found in the system reliability design phase. The work is funded by the National "863" Project.Main contents and contributions of this paper are as follows:As tolerance analysis theory is concerned,the traditional methods like Worse-case analysis,moment method,MC analysis are studied systemic,tolerance analysis method based on interval mathematics is discussed emphatically. Besides,applications and algorithms(including Importance Sampling,Genetic Algorithms) of tolerance analysis are reviewed.On the condition of absence of feature degradation modal of parts and effective aid tool,the failure mechanism and reliability model of parts in power module are analysised,and with the result of failure analysis and empirical data the life model of metalized electrode capacitor is figured out,which is proved to be Weibull distributions.According to design qualifications of power module,tolerance analysis model based on the stochastic programming is proposed. Tolerance distributions are simulated by computer,a computer simulation program based on MC method has been used to analysis the model. After calculating part tolerance compounds of five levels,get acceptable capacitor and induce tolerance level compounds to assure the steady operation of power modules at certain confidence level. These will provide references to reliability design and analysis work of the power conditioning system.At last one frame of reliability simulation platform are proposed to simulate reliability level of circuits with degradation and other failure modes. It will help to take full use of test data and empirical models to predict the trend of system failure rate. |
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