A linear analog fault diagnosis approach by means of fault dictionary is presented to overcome the three major defects in classic fault dictionaries. First, a fault dictionary using node-voltage-deviation-ratio vectors as fault signatures is constructed. The dictionary can detect both the hard and soft faults for each single faulty component in linear circuits, and has some significant features such as less simulation runs, minimal storage space and wide diagnosis scope. Second, how to extend some points of view in geometry to analog fault diagnosis area is discussed, and three geometric models based on the node-voltage-deviation-ratio vectors are designed for faults isolation in case of considering tolerances. Last, two examples are given to verify the methodology. The promising experimental results manifest the correctness and effectiveness of the approach proposed in this paper.%针对传统故障字典法的3个主要缺陷,建立了以节点电压增量比作为特征向量的故障字典,该字典能对电路中每个元件的硬故障和软故障作出诊断,具有测前模拟次数少、占用存储空间小、诊断范围宽的特点.针对由于元件参数容差导致故障定位难度大的问题,阐述了如何将几何学中的一些观点应用到故障诊断中,并建立了3个故障隔离的几何模型;最后通过实例验证了该诊断理论和方法的正确性和有效性.该方法适用于线性模拟电路.
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