Sneak Circuit Analysis Research Articles

Bidirectional power flow in an electric vehicle using predictive control algorithm including sneak circuit analysis

Bidirectional power flow in an electric vehicle using predictive control algorithm including sneak circuit analysis

Sneak circuit analysis based performance optimization for ZVT PWM boost converters

Sneak circuit analysis based performance optimization for ZVT PWM boost converters

Graph Theory-Based Sneak Circuit Analysis and Trigger of Semi-DAB With Parasitic Parameters

Parasitic parameters and dynamic sneak paths would lead to unexpected phenomena, exerting negative impacts on the reliability and safety of Semi-dual active bridge (S-DAB) DC-DC converter. Therefore, a graph theory-based sneak circuit characteristics analysis, trigger mechanism, and suppression method of S-DAB are proposed in this paper. The complete current-based sneak path modeling is obtained, combining both bridges via high frequency link inductor current. Then, the accurate sneak modalities are proposed and detailed, including high-order and first-order sneak operating modalities. Thus, the possible sneak circuit phenomena are detailed to explain the negative impact on operating characteristics, depicting the chaotic phenomenon caused by the dynamic characteristics of bus capacitance. Then, the trigger mechanism and timing are proposed and indicated in time series. Moreover, the suppression conditions are derived by optimizing modulation parameters and parasitic parameters. Compared with the previous researches, the modeling, analysis, and suppression of sneak operation are more detailed and general in this paper to improve the stability and reliability of S-DAB. Finally, experimental results verify the theoretical analysis. The variation range of converter output with proposed suppression method is reduced by 65.4%, and the bifurcation chaos can be suppressed effectively.

Research on the sneak circuit analysis method of a thermal system based on energy flow

AbstractBased on the energy flow analysis method, this paper establishes the relationship between the heat accumulator and the thermal system from the perspective of heat transfer. Different types of heat accumulators are converted into different equivalent models based on energy flow, the existing sneak circuit analysis methods based on energy flow are optimized, and the starting point and end point of path search are redefined. The energy flow‐based correlation method proposed in this paper is applied to a system with two different types of heat accumulators. The results show that the sneak circuit analysis method based on energy flow proposed in this paper can search for more paths and discover new sneak circuits on the basis of the original method. Therefore, the new method is feasible and effective.

The Application of Sneak Circuit Analysis on Chemical and Volume Control System

In the chemical and volume control system (RCV) of nuclear power plant pipelines are very complex, there are many valve control nodes. These make the probabilistic risk of unexpected situation rather high in design and running. In order to increase the reliability and safety of the system in design and running, the sneak circuit analysis technology is applied in gas and liquid pipelines of RCV to find latent path and temporal sequence in design and running. Improvements and advices are given to avoid these latent risks in design and running.

President's Message

The recent International System Safety Conference (ISSC) in Albuquerque, New Mexico was a thought-provoking event.
 Professor Edward Gibson gave the first keynote address. He described the engineering programs at Arizona State University (ASU) and some possible relations with the system safety discipline. Members of the Executive Council (EC) had additional meetings with Dr. Gibson to explore including system safety concepts in the school’s engineering curriculum, as well as the relationship between ASU and the ISSS.
 One of the most venerable members of our Society, John Rankin, gave several presentations on hazard analysis. He also provided a viewing of the movie Fate is the Hunter and explained how it helped inspire him to invent Sneak Circuit Analysis.
 The Conference featured many excellent papers and tutorials. One that received a good deal of positive commentary was on the topic of “gamification” in teaching software safety analysis. The authors, Brian Connell and David Musgrave, have developed an entertaining and effective way to train on this topic.

Sneak Circuits in Power Converters: Concept, Principle and Application

“Sneak Circuit” is defined as the unexpected path or operational status in an electric or electronic circuit due to the limitation or oversight in design by human. The sneak circuit can be triggered to operate under certain conditions, which results in an unwanted or unintended action. As power converter is an artificially designed system, it is undoubted that sneak circuits exist in power converters, while sneak circuit phenomena have been proved in some typical power converters. In order to improve safety and reliability of a power electronic system, it is necessary to understand thoroughly the sneak circuit in power converters under all possible practical conditions. Thus, this paper aims at providing a brief review of sneak circuits in power converters, and summarizes the sneak circuit analysis (SCA) methods based on the graph theory. Finally, some applications on power converters by making use of the SCA principle of sneak circuit analysis are included.

Sneak Circuit Analysis: Lessons Learned from Near Miss Event

Sneak Circuit Analysis is intended for critical applications which are essential to mission success and safety. A sneak condition will occur when a designed circuit inhibits a wanted function or results in an unwanted function. Sneak conditions originate from one of the four following scenarios: a sneak path resulting in a flow of electrical current along an unexpected route; a sneak timing that may cause the activation of some desired/designed functionality at an unexpected time; a sneak indication in monitoring functions that may result in an ambiguous or false display of system operating conditions; and lastly, a sneak label which may induce operator error due to inappropriate instruction. This paper introduces a near miss event that occurred in the Sao Paulo monorail which was caused by a sneak time condition. Root cause analysis and design modifications are also discussed in the paper.

Research of Node Importance for Sneak Circuit Analysis Based on Quantitative Model

Sneak Circuit Analysis (SCA) is a technical means. It can solve practical problems in engineering, provide security of the system. To solve the problems of traversal qualitative for sneak circuit analysis, the importance of switch nodes in circuit network was proposed based on the quantitative analysis model of sneak circuit. Quantitative models for sneak circuit analysis were established and the circuit network's composition method was determined based on circuit topologies and line information. Because of the limitation of full traversal method, polycondensation degree was applied to evaluate node importance in sneak circuit analysis. The importance of switch nodes was recognized by taking degree of polycondensation as an evaluation indicator. Key nodes take core analysis algorithms and the other nodes use adding analysis algorithms. To illustrate the effectiveness of this method, emulation of switches’ state was taken as the example of sneak circuit compared with traditional methods of identifying node importance such as node degree and betweenness.

Neural Network Ensemble Based on Clonal Selection Algorithm for Sneak Circuit Analysis

The paper proposed a novel neural network ensemble algrithm (NNNEA) whose individual was generated by clonal selection algorithm. NNNEA can produced individuals of ensemble with better difference than other algrithm. NNNEA was used for predicting ciruit functions and finding sneak circuit. The inputs of NNNEA are states of switches, and the outputs are states of functional components. NNNEA predicted all possible functions of circuit. The sneak circuits can be discovered by comparing the predicted with designed functions. Although there are several limitations of NNNNEA, the results revealed that NNNNEA can exactly discover sneak circuits.

Sneak Circuit Partition Analysis Algorithm Based on Network Flow Simulation

Sneak circuit analysis method is moving to intelligent and automation direction, the method based on network flow simulation has some representation. With the expansion of the circuit system topology and the increasement of the component's amount, the analysis time increases and the efficiency is difficult to be guaranteed. To solve this situation, the circuit system can be divided into some blocks for analysis. Based on the network flow simulation model, the adjacency matrix of circuit system is established. The analysis matrix of circuit system is obtained by the simplification of the adjacency matrix; use the analysis matrix as the network model for circuit system partition analysis. Select appropriate point from the network cutting point as the partition point, the circuit system can be divided into some sub-blocks by removing these points. Circuit system stratified analysis principle is proposed; determine the division method and analysis objectives of each convention level. This method can correctly analysis sneak circuit problem for circuit system, effectively reduce the analysis time and improve the analysis efficiency. It can be taken as an effective complement of sneak circuit analysis method based on network flow simulation for engineering application.

Model-based methodology using modified sneak circuit analysis for power electronic converter fault diagnosis

This study presents a novel research methodology and approach for diagnosing pertinent failures for power electronic converters. The concept of the generalised connection matrix for a sneak circuit analysis is used in this research. A novel modification to this process shown in this study produces a usable feature that provides unique signatures under fault scenarios and could be used to diagnose faults. The novelty lies in using component currents to form the generalised connection matrix. This study presents the results obtained using data collected from fault scenarios on a hardware set-up for the dc–dc buck converter.

Safety Analysis for Complex Thermal System Based on Sneak Path Technique

Sneak circuit analysis technique is an important analytical tool that can promote the safety and reliability of the circuit control system. It applied to aerospace control engineering widely now. Comparing a thermal system and electric circuit system, the concept and method of sneak path analysis for complex thermal system are proposed by this paper. And the development and application vista of thermal system sneak path analysis and specific implementation are analysed.

ENSEMBLE OF NOVEL NEURAL NETWORK BASED ON CLONAL SELECTION ALGORITHM FOR SNEAK CIRCUIT ANALYSIS

Neural network was introduced to sneak circuit analysis (SCA) in previous works. However, it may generate suspect results which were hard to explain. To overcome the shortcomings, this paper proposed a novel neural network model based on circuit architecture, named CArNN, which is used as an individual of an ensemble. In CArNN, neurons represented system components, and weights represented the joints between components. Models of neurons are sigmoid functions. Clone selection algorithm was used to train CArNNs population. The trained antibodies were used as individuals of an ensemble. The inputs of CArNN are states of switches, and the outputs are states of functional components. Ensemble predicted all possible functions of circuit. The sneak circuits can be discovered by comparing the predicted and designed functions. The results revealed that CArNNs can exactly discover sneak circuits.

Sneak Circuit Analysis Based on Novel Coadjacent Neural Network Model for Reliability Control of Complex System

摘要: 潜在问题是影响大型复杂系统安全性、可靠性的重要因素. 神经网络是一种新的潜在问题分析方法, 但是其分析结果难以解释. 本文提出了一种基于电路结构的神经网络模型 (Neural network model based on circuit architecture, CArNN), 将 CArNN 作为个体进行集成, 形成神经网络集成用于潜在问题分析. 对 CArNN 模型的鲁棒性进行了分析, 提出了两个保证模型鲁棒性的约束条件. 利用此方法对一个经典电路进行了分析, 结果显示, 此方法对潜在电路的正确识别率达到94\%. 关键词: 潜在问题分析 / 可靠控制 / 神经网络集成 / 克隆选择算法 / 鲁棒性分析 / 泛化性能

A language for functional interpretation of model based simulation

Functional modelling has been in use for a number of years for the interpretation of the results of model based simulation of engineered systems. Its use enables the automatic generation of a textual design analysis report that interprets the results of qualitative (or numerical) simulation in terms of the system’s purpose. We present a novel functional description language that increases the expressiveness of this approach, increasing the range both of systems and design analysis tasks for which the approach can be used. The language also allows closer integration of functional modelling into the design process. The language allows a device function to be decomposed either in terms of subsidiary functions or required effects. We discuss the use of such alternative decompositions and propose a logic of functional description that is used to underpin the proposed language. The language has been used in the interpretation of electro-mechanical, hydraulic and fluid transfer systems in the automotive and aerospace industries to support Failure Modes and Effects Analysis, Sneak Circuit Analysis, and Diagnosis design analysis tasks. The language is not inherently restricted to these applications and the paper makes use of indicative examples from other domains.

Design Failures in Aerospace Electrical Systems(The Identification of Sneak Circuits)

The malfunction or failure of an aircraft electrical system because signal or power flow paths were unintentionally designed into the electrical circuit, is known to be the cause of several major failures of engineering systems. These unintentional signal or power paths are called sneak circuits. The nature of Sneak Circuits was first considered after they had been identified as the cause of some spectacular and expensive rocket failures in the United States space programme. This paper reviews the status of Sneak Circuit Analysis (SCA) and presents a general systematic approach the author has devised to identify sneak circuits during the circuits design phase. The application of the method of SCA is illustrated with a case study. The paper makes a case to take the investigation of an electrical failure or malfunction beyond the identification of a failed component to include a search for possible sneak circuits. The obvious fact that could result from the discovery of a sneak circuit is the shift in legal responsibility from the component manufacturer to the circuit designer.

Hierarchical functional reasoning

This paper discusses the use of hierarchies of function in reasoning about automotive electrical systems. Such hierarchies enable more powerful reasoning for applications such as diagnosis, failure mode and effects analysis, sneak circuit analysis and design verification, while also structuring the domain and thus reducing the complexity at any one level. The context of this discussion is the existing AutoSteve system for performing these tasks. The AutoSteve system works with single level electrical schematics, one schematic for each subsystem in the car, and with a set of functional labels for each subsystem. The functional labels can be used to interpret what is happening in a qualitative simulation of the circuit.

Function-directed electrical design analysis

Functional labels provide a simple, but very reusable way for defining the functionality of a system and for making use of that knowledge. Unlike more complex functional representation schemes, these labels can be efficiently linked to a behavioral simulator to interpret the simulation in a way that is meaningful to the user. They are also simple to specify, and highly reusable with different behavioral implementations of the system's functions. This claim has been substantiated by the development of the FLAME application, a practical automated design analysis tool in regular use at several automotive manufacturers. The combination of functional labels and behavioral simulator can be employed for a variety of tasks—simulation, failure mode and effects analysis (FMEA), sneak circuit analysis, design verification, diagnostic candidate generation—producing results that are very valuable to engineers and presented in terms that are easily understood by them. The utility of functional labels is illustrated in this paper for the domain of car electrical systems, with links to a qualitative circuit simulator. In this domain, functional labels provide a powerful way of interpreting the behavior of the circuit simulator in terms an engineer can understand.

The investigation of malfunctions and failures in electrical systems

The malfunction or failure of an electrical system because unintentional signal or power flow paths were incorporated in the electrical circuit design is known to be the cause of several major failures of engineering systems. These unintentional signal or power paths are known as sneak circuits. The nature of sneak circuits was first considered after they had been identified as the cause of some spectacular and expensive rocket failures in the United States space programme. This paper reviews the status of sneak circuit analysis (SCA) and presents a general systematic method the author has devised to identify sneak circuits. The application of the method of SCA is illustrated with a case study. The paper makes a case to take the investigation of an electrical failure or malfunction beyond the identification of a failed component to include a search for possible sneak circuits. The obvious fact that could result from the discovery of a sneak circuit is the shift in legal responsibility from the component m...