基于灵敏度分析和GA的模拟电路故障诊断

为了实现模拟电路故障的检测,提出了将灵敏度分析与遗传算法结合的算法。该算法利用灵敏度分析估算元件参数偏移量求解故障元件,并用遗传算法寻求最优解。提出改进的自适应遗传算法,实验结果表明该方法对容差模拟电路的多软故障诊断具有较好的诊断率。     

一种新的模拟电路多故障诊断方法

本文提出了一种新的模拟电路多故障诊断方法——组合优化模拟退火法。该方法采用组合优化的思想,综合参数辨识法与故障验证法这两类故障诊断方法的优势,提出了解决测试端口个数小于元件参数个数的诊断方程欠定问题的目标函数,通过模拟退火优化算法对目标函数寻优,可定出故障元件值及非故障元件的容差值,并保证所得解收敛于全局最优。     

基于遗传算法的容差模拟电路故障诊断

给出了用于模拟电路元件参数识别的多频传递函数法的过程,并对故障诊断方程的可解度进行了分析,在此基础上,将诊断方程的求解转化为非线性函数的优化问题,并运用改进的遗传算法来解决这个问题,算法实例表明该方法简化了故障诊断方程的求解过程,加速了容差电路故障元件的定位,有一定的应用价值。     

非线性直流故障电路的规范型分段线性分析

本文应用规范型分段线性法进行了非线性直流故障电路的分析,求解了预先选为测试端口的端口电压值。该法需要的贮存量少,经有限步即可得到解答,计算效率高,并且适用于含有多端口非线性元件的电路,是一个故障诊断测试前模拟法,是分析测试前故障电路的好方法。     

电流源激励下的模拟电路端口电压测试方法

文章研究了电流源激励下，二端口网络的输入端电压和输出端电压随网络中元件参数变化时相互之间的关系，并在此基础上提出了一种模拟电路故障诊断新方法。该方法不仅能够同时诊断元件的硬故障和参数偏移故障，而且能够同时运用于直流测试和交流测试。     

基于神经网络与证据理论的模拟电路故障诊断

论述了利用多类电量测试信息、应用神经网络与D-S证据理论实现模拟电路故障诊断的基本原理,提出了一种基于可测点电压与不同测试频率下的电路增益经决策层信息融合的故障诊断新方法.分别利用此两类测试信息,各用一个独立的改进BP网络对电路进行初步诊断,再运用所提融合诊断算法实现故障定位.模拟实验结果表明:所提方法对硬故障与元件参数偏移较小的软故障均适用,故障定位准确率高.     

一种基于多频灵敏度分析的模拟电路K故障诊断方法

在模拟电路灵敏度分析的基础上，提出了多频灵敏度K故障诊断方法，详细说明了多频灵敏度K故障诊断方法的原理和步骤。针对模拟电路中最常见的双故障进行了电路仿真，仿真结果说明了该方法的有效性。     

基于FastICA算法的电路故障诊断方法

在电路故障检测中针对元件种类较少且同一种元件重复出现的电路,提出基于FastICA(fast independent component analysis)算法的故障诊断方法。该方法首先对电路中的元件进行分类再按信号叠加算法分组建立测试电路,电路正常工作时测试电路不给电。利用FastICA算法对测试信号进行盲分离,初步判断分离结果后与预先建立的元件故障信号库Mf的信号作相关分析判定故障类型。这种故障诊断方法简单易实现且对元件类型没有限制,在检测过程中元件之间没有相互干扰可确保诊断的准确性。仿真表明该方法能有效判断出电路的故障情况。     

一种多传感器信息融合电路故障诊断方法

针对电路故障元器件诊断不确定性问题,提出了电路元器件故障诊断的多传感器D-S信息融合方法。该方法通过测量被诊断电路中元件的电压、温度两个参数,获取二个传感器对待诊断元件的信度函数,然后得出融合信度函数,从而确定故障元件。诊断实例结果证明了该方法的有效性。     

基于BP神经网络的模拟电路诊断系统研究

以现代测试技术、信号处理、信息融合等理论为基础,以神经网络在模拟电路故障诊断中的应用为主线,详细讨论BP神经网络在模拟电路故障诊断中的应用和故障特征提取方法.采用多频组合法建立了故障样本集.对选定的待测电路在元件存在容差的条件下,仿真验证了BP神经网络应用于模拟电路故障诊断的可行性.     

Analog circuit diagnosis based on the nullor concept and multiport description of the circuit

The subject of this paper is the fault diagnosis of analog circuits based on the use of nullor concept. The fault location technique presented in the paper can be implemented in the general-purpose analysis program which provides many advantages, of which the most important is the automation of the diagnosis process. A simulation based diagnosis model can be obtained by introducing the norators across the potentially faulty elements and the fixators at the accessible nodes. A practical problem that arises when using this nullor diagnosis model is a lack of an efficient procedure for localization of multiple faults. In the proposed diagnosis technique, the online computational requirements are reduced by introducing a diagnosis model that contains accessible nodes only. The diagnosis model is obtained from the original circuit using relationships among the measured voltages and compensated currents of the faulty elements. The proposed faulty location technique is validated on a benchmark example.     

A Classical Parameter Identification Method and?a?Modern Test Generation Algorithm

Many methods have been presented for the testing and diagnosis of analog circuits. Each of these methods has its advantages and disadvantages. In this paper we propose a novel sensitivity analysis algorithm for the classical parameter identification method and a continuous fault model for the modern test generation algorithm, and we compare the characteristics of these methods. At present, parameter identification based on the component connection model (CCM) cannot ensure that the diagnostic equation is optimal. The sensitivity analysis algorithm proposed in this paper can choose the optimal set of trees to construct an optimal CCM diagnostic equation, and enhance the diagnostic precision. But nowadays increasing attention is being paid to test generation algorithms. Most test generation algorithms use a single value in the fault model. But the single values cannot substitute for the actual faults that may occur, because the possible faulty values vary over a continuous range. To solve this problem, this paper presents a continuous fault model for the test generation algorithm which has a continuous range of parameters. The test generation algorithm with this model can improve the treatment of the tolerance problem, including the tolerances of both normal and faulty parameters, and enhance the fault coverage rate. The two methods can be applied in different situations.     

Fault Diagnosis of Analog Circuits Using Systematic Tests Based on Data Fusion

An analog fault diagnosis approach using a systematic step-by-step test is proposed for fault detection and location in analog circuits with component tolerance and limited accessible nodes. First, by considering soft faults and component tolerance, statistics-based fault detection criteria are established to determine whether a circuit is faulty by measuring accessible node voltages. For a faulty circuit, fuzzy fault verification is performed using the accessible node voltages. Furthermore, using an approximation technique, the most likely faulty elements are identified with a limited number of circuit gain measurements at selected frequencies. Finally, employing the D-S evidence theory, synthetic decision is made to locate faults according to the results of fault verification and estimation. Unlike other methods which use a single diagnosis method or a particular type of measurement information, the proposed approach makes use of the redundancy of different types of measurement information and the combined use of different diagnosis methods so as to improve diagnosis accuracy.     

基于小波高频系数统计特征的电路故障诊断

对故障电路进行特征提取与分类是模拟电路诊断的两个重要环节。现有方法多对时域响应信号进行小波变换以提取故障特征,并用神经网络或支持向量机方法实现对故障进行分类。为提高模拟电路故障诊断率,提出一种新的特征选取方法:在模拟电路的时域响应中对其进行小波变换,并对变换得到的高频细节系数统计平均值、标准偏差、峭度、熵和偏斜度等统计特征,并建立以支持向量机为分类器的故障诊断系统。以两种常见电路为例,实验结果表明,提出方法对常见电路进行故障诊断,准确率得到提升,精度达到99%以上,优于传统单纯小波系数分析方法,适用于模拟电路的故障诊断。     

模拟电路故障诊断的结点电压灵敏度比值法

在证明线性电路中结点电压变化量比值等于结点电压灵敏度比值的基础上,提出了结点电压灵敏度比值法,通过结点电压变化量比值和结点电压灵敏度比值的比对确定电路的故障元件。理论分析和实验结果表明,该方法算法简单、诊断速度快,在可测点受限条件下具有较高的诊断精度,特别适合大规模线性模拟电路的故障诊断和测试。     

Testing of Synchronizers in Asynchronous FIFO

This paper presents a test method for testing two-D-flip-flop synchronizers in an asynchronous first-in-first-out (FIFO) interface. A faulty synchronizer can have different fault behaviors depending on the input application time, the fault location, the fault mechanism, and the applied clock frequency. The proposed test method can apply the input patterns at different time and generate capture clock signals with different frequency regardless of phase-locked loop (PLL) of the design. To implement the proposed test method, channel delay compensator, delayed scan enable signal generator, launch clock generator, and capture clock generator are designed. In addition, a well-designed calibration method is proposed to calibrate all programmable delay elements used in the test circuits. The proposed test method evolves to several test sections to detect all possible faults of the two-D-flip-flop synchronizers in the asynchronous FIFO interface.     

基于电流测试的混合电路故障诊断

在运用小波神经网络进行混合电路故障诊断的过程中,测试参数的选取至关重要。研究了一种基于电流测试的故障诊断。该方法即通过PSPICE模拟电路的静态及动态电流信息,再通过小渡神经网络的结合,证明了该方法在混合电路故障诊断中的可行性,为提高混合电路的故障诊断率提供了一种新的方法。     

A Method on Analog Circuit Fault Diagnosis with Tolerance

In this paper, it is proved that the direction of the node-voltage difference vector, which is the difference between the node-voltage vector at faulty state and the one at the nominal state, is determined only by the location of the faulty clement in linear analog circuits. Considering that the direction of the node-voltage sensitivity vector is the same as the one of the node-voltage difference vector and also considering that the module of the node-voltage sensitivity vector presents the weight of the parameter of faulty element deviation relative to the voltage difference, fault dictionary is set up based on node-voltage sensitivity vectors. A decision algorithm is proposed concerned with both the location and the parameter difference of the faulty element. Single fault and multi-fault can be diagnosed while the circuit parameters deviate within the tolerance range of 10 %.     

模拟电路k故障诊断理论的数学模型

故障诊断理论是模拟电路故障诊断理论的一个重要分支。现已提出的k故障诊断方法有支路法、节点法、割集法、回路法以及网孔法,这些方法都能较好地完成故障定位与故障定值,并在可测性设计方面有了较大的发展,但是这些方法还没有一个统一的理论模型。本文对这几种方法进行了总结和概括,提出了k故障诊断理论的统一数学模型,这项研究工作的目的是为了加强k故障诊断理论的系统性和严密性,并为更深入的研究和实践提供了理论依据。     

一种模数混合电路故障诊断新方法

把模拟电路故障诊断的子网络撕裂诊断法与数字电路故障诊断的伪穷举测试法相结合．提出了一种应用于模数混合电路的故障诊断方法。其诊断思想是把串联形式的混合电路，划分成模拟和数字电路两部分．并分别进行诊断。该方法计算量小、诊断定位精度高，适合于工程应用。