A Study On Safety Failure Risk And Hierarchical Control Measure Of Electric Vehicle

Developing electric vehicles is one of the important measures to achieve green environmental protection.With the rapid increase in the production and sales of electric vehicles,the problem of safety failure has become increasingly prominent.The safety failure of electric vehicles may bring personal injury,economic losses and negative social impacts.Therefore,it is of great significance to study the safety failure of electric vehicles,analyze the cause mechanism,evaluate the risk of fire and explosion accidents of electric vehicles and suggest hierarchical control measures to reduce the safety failure risk of electric vehicles and prevent the occurrence of fire and explosion accidents of electric vehicles.Firstly,the concept of safety failure of electric vehicles is introduced,and it is divided into: the failure of the functions of electric vehicles that cannot be properly played and the failure of electric vehicles that lead to destructive consequences.Based on energy accident release theory and cross-track theory and combined with the example statistics of electric vehicle safety failure in recent years,the transmission of safety risk of electric vehicles cannot be separated from human unsafe behavior,unsafe conditions and harsh environment,and the transmission process of electric vehicle safety failure risk is analyzed.A bow-tie model for safety failure of electric vehicles is constructed to analyze the causes of safety failure of electric vehicles and explore the occurrence mechanism of electric vehicles safety failure.It is found that,electric vehicles may be at risk of safety failure from the stages of design,manufacture and use,maintenance.Under the influence of the cascading failure and common cause failure,some electric vehicles component and system example calculations,both in the cascading failure and common cause failure make the system failure degree increase.Secondly,according to the BD electric vehicle fire and explosion accident report,based on the characteristics of the BD electric vehicle,the electric vehicle system is divided into subsystems of the vehicle control subsystem,drive motor subsystem(including chassis and wheels,motor),auxiliary subsystem,power subsystem and infrastructure subsystem.Based on the fuzzy theory and the failure mode and effect analysis,the method of combining the failure mode and effect analysis of the fuzzy theory is established to evaluate the risk of the explosion of the BD electric vehicle,and calculate the risk severity,frequency and detection of each failure mode and fuzzy risk priority value.It is found that the power subsystem is the biggest risk source,followed by the infrastructure subsystem,the drive motor subsystem,the auxiliary subsystem,and finally the vehicle control subsystem.Among the 29 failure modes,the battery pack short circuit,battery thermal runaway,and charging pile without overload are also the main failure modes with high risk.On the basis of the traditional two dimensional risk matrix,the dimension of the detection degree is added to build a three dimensional risk matrix model through matlab,presenting the variation risk value obtained when the three elements of risk severity,frequency and detection are combined in different ways.The variation of risk values of different combinations of risk severity,frequency and detection is presented,and a rapid grading of the fire and explosion risk of electric vehicles has been achieved.In addition,combined with the risk calculation of the short-circuit risk of the BD electric vehicle air-conditioning system,the three-dimensional risk matrix and risk level of the short-circuit risk of the BD electric vehicle air-conditioning system are obtained.Thereby the visualization of the risk is achieved.Finally,based on the qualitative analysis results of the safety failure risk of electric vehicles and the quantitative evaluation results of the explosion risk of BD electric vehicles,the corresponding hierarchical control countermeasures are proposed.