Research On Enhancement Technology Of BIT Diagnosis Capacity In Complex Electromagnetic Environment

Complex electromagnetic environment(CEME)is constituted of multifarious electromagnetic sources and various kinds of stresses,which competitively affect the electric equipment,in order to cause the phenomena of interference,disturbance,damage and etc.Furthermore,the equipment features signals and Built-in-test(BIT)testing course are influenced,so CEME is one main factor to decline BIT system testing capacity and to cause false alarm(FA).Based on the mechanism how various types of electromagnetic stresses influence the BIT diagnosis results,this dissertation focuses on the research of enhancement technology of BIT diagnosis capacity,so that the CEME influence on equipment BIT could be reduced.The purpose is to enhance the BIT diagnosis capacity in CEME and reduce FAs.The main contents of the dissertation are as follows.1.The concept of CEME influence extent is determined and the extent evaluation method is proposed.The electromagnetic stress field simulation model is established.The relationship of various stresses and BIT results are researched,and then the enhancement approaches of BIT diagnosis capacity in CEME are analyzed.Firstly,the effect mechanisms and effect influences of various electromagnetic sources are summarized.The concept of CEME influence extent is defined,then the extent evaluation method and the stress grades division methods are proposed,in order to estimate the stress influence and BIT diagnosis capacity.Secondly,it is established the simulation model of the electromagnetic stress field of certain electric device with the outer box and inner circuit,to get the stress concentrations by analyzing stress distributions.The consequence could be the foundation of the stress influence mechanism research and corresponding confirmatory experiments.Then,the testing and diagnosis model of the threshold BIT system is established and analyzed,the intermittent fault alarm(IFM)principles are analyzed,in order to illustrate that the electromagnetic environment stress is the main factor to cause IFMs.Based on CEME effect influences,the electromagnetic stresses are divided into three types of interference,disturbance and damage.Finally,with the relationship research between stresses and BIT results,the enhancement approaches of BIT diagnosis capacity in CEME are analyzed and given.2.To solve the problem that the interference electromagnetic stress influences BIT testing signal,the effect influence of this stress on BIT diagnosis results is analyzed.From the view of effective testing information extraction and comprehensive falut diagnosis,it is proposed the anti-jamming technologies of BIT diagnosis capacity enhancement with CWT-SVM(continuous wavelet transform-support vector machine).(1)It is analyzed the effect influence of interference electromagnetic stress on electric equipment,and then the mechanism and influence of this kind of stress on BIT detection and diagnosis results are researched.Furthermore,it is given the enhancement approaches of BIT diagnosis capacity with interference electromagnetic stress.(2)Aiming at the problem that the interference electromagnetic stress influences BIT testing signal,it is proposed the anti-jamming technologies of BIT diagnosis capacity enhancement based on CWT-SVM.Firstly,the representation characteristics of interference stress are analyzed to optimize the representation characteristics of electromagnetic stress for BIT diagnosis and decision.Meanwhile,the CWT is used for noise reduction of BIT testing signals,to extract the sensitive features of unit under test(UUT)faults.On these bases,the nonlinearity diagnosis method by SVM is used to enhance BIT diagnosis capacity,with electromagnetic stress features and UUT faults sensitive features.Finally,the testing experiment of electric connector faults is done,the anti-jamming technologies of BIT diagnosis capacity enhancement is certificated by the data processing results.3.According to the equipment intermittent fault and BIT false alarms by disturbance electromagnetic stress,the stress characteristics are analyzed.From the view of intermittent fault diagnosis and false alarm recognition,it is proposed the BIT diagnosis capacity enhancement technology with false alarm recognition.(1)With common characteristics analysis of the disturbance sources,the electro-static discharge(ESD)source is chosen as research object.By establishing and analyzing the ESD effect model,the effect mechanism how ESD stress influences electric equipment is researched.Based on ESD model and experiment results,the stress influence on BIT diagnosis results is analyzed,and then the enhancement approaches of BIT diagnosis capacity are analyzed and given.(2)Because the disturbance electromagnetic stress is the main cause of intermittent faults and false alarms,it is proposed the BIT diagnosis capacity enhancement technology with false alarm recognition.Firstly,based on fault features and electromagnetic environment parameters,the features extraction method by fault feature contribution is proposed,in order to extract effective features for BIT testing data under disturbance stress.Then,with the input of BIT testing data feature and electromagnetic environment parameters,it is proposed the BIT false alarm recognition method based on AIS(Artificial Immunity System),in order to recognize false alarms and enhance BIT diagnosis capacity.Finally,An ESD experiment is performed with objects of the radar electric source and BIT system.The false alarm recognition technology is used to process the BIT testing data and environment data,and the results show that the technology is feasible and effective.4.According to the component damage by damage electromagnetic stress in CEME,the influence factors of electromagnetic damage is analyzed.From the view of equipment account degradation,it is proposed the BIT diagnosis capacity enhancement technology with electromagnetic damage evaluation.(1)The influence factors of electromagnetic damage is analyzed from the view of electromagnetic effect stress and equipment suffering capacity.The existing failure physical model of electromagnetic damage is analyzed to illustrate the accelerating effect of electromagnetic stress.Based on these results,it is analyzed the influence of damage electromagnetic stress on BIT diagnosis results.(2)In order to enhance the BIT diagnosis capacity under damage electromagnetic stress,it is proposed the BIT diagnosis capacity enhancement technology with electromagnetic damage evaluation.Firstly,the representation characteristics of electromagnetic damage are established by analyzing the probability and extent how electromagnetic stress influences damage.Then,based on electromagnetic damage mode with degradation,it is proposed the electromagnetic damage evaluation method to transfer the stress to uniform degradation.Finally,it is proposed the diagnosis method with AIS based on data propagation,in order to enhance the BIT diagnosis capacity under damage electromagnetic stress.The technology has been proved by electromagnetic damage simulation experiment with ESD stress.In conclusion,with the object of interference,disturbance and damage stresses,this dissertation researches the characteristics and influences of various electromagnetic stresses,in order to propose BIT diagnosis capacity enhancement technologies.The results of simulation and practicality experiments show that these methods are correct and feasible,that means high academic research value and projective application value.