G参数诊断准则的理性分析

Validity Analysis of the G－Criterion for Diagnosis

本文研究一种模拟电路故障诊断经典方法（即Ｇ参数诊断法）的正确性和合理性．研究表明：（１）估计Ｇ参数的数学模型是错误的；（２）由错误模型所得的Ｇ参数估计集必定是真实Ｇ参数集的有偏估计；（３）假如不满足严格的约束条件，Ｇ参数诊断法将给出错误的诊断结论．本文还给出了Ｇ准则能否正确诊断的预报公式，该公式很容易由电路标称数据计算．

This paper is to study the validity of the G-diagnosis algorithm that has been regarded as a classical algorithm for faulty diagnosis in analog circuits. The results of this study indicate that: (1)wrong mathematical models are used to estimate G-parameters ; (2)the estimated Gparameters must be biased against actual G-parameters;(3)the G-algorithm will give mistaken diagnosis conclusions if harsh conditions can not be satisfied. The paper proposes formulas,which are easily calcuated with nominal data of circuits,to forecast if the G-diagnosis algorithm can locate faults correctly or not.