Fault Diagnosis And Implementation Of Electric Vehicle Lithium-ion Battery System

As the pressure of the resources and environment increases, the electric vehicle isconsidered as one of the most promising advanced technologies. Power battery is the keycomponent in electric vehicles, and also the main source of failure. The research in powerbattery fault could make the diagnosis more effect, and predict the occurrence of failure,improve the vehicle power battery life. Based onextended-range electric vehicle（EREV）school bus, the battery system common faults, fault cause and fault restoration methods canbe achieved.Firstly, viathe fault tree analysis （FTA）, we can identify the cause of common faultof the different battery systems. Via the failure mode and effects analysis （FMEA）, wecan make the preliminary judgment about possible consequences of all kinds of potentialfailure and put forward the corresponding troubleshooting measures.Secondly, via improve the RC equivalent circuit model （ECM）, cell model and thermalmodel can be established. Via4kind cell （Cell_Norm, Cell_Cap, Cell_Rt,Cell_SOC）,usingthe simulation data of the battery system at different initial SOCsupport the batterysystem fault diagnosis.Thirdly, the wavelet analysis is used in96gruops of simulation data in cell voltage, celltemperature, cell SOC and cell power loss. The energy of the wave in different node of thewavelet analysis can be seen as the diagnosis feature vector. A BP neural network is designedto detect the cell inconsistency fault.Fourthly, the hardware circuit related to fault detection of battery management system isdesigned to process failure, including equilibrium circuit, fan drive circuit and insulationdetection circuit. The software of fault diagnosis system also is designed, including the faultclassification, fault grading, fault storage, broadcasting and display, achieving the faultdiagnosis.Finally, the upper computer LabVIEW application of battery management system isdesigned. The application is event triggered data steams software system, which can displaythe status of the power battery system and also the data of BMS fault diagnosis. This uppercomputer software can validate the fault diagnosis system built in BMS, and provide thesufficient data for fault diagnosis system analysis and improvement.