Research On The Battery Fault Monitoring System Of Battery Electric Vehicle

With the severe situation of the environment,more and more countries pay their attention to battery electric vehicles in the field of automotive research.Battery electric vehicles bring both convenience and potential risks to the driving process.In order to ensure the safety of battery electric vehicles in the driving process,the research on battery fault monitoring system of battery electric vehicle is of great significance.This paper chooses the lithium battery of battery electric vehicle Baojun E100 as the research subject,analyses the main fault of the battery,and puts forward the fault diagnosis method of the fuzzy fault tree contraposing the disadvantage of traditional fault tree whose probability value is fixed.Based on the general requirement of the system,this paper studies the CAN communication protocol,hardware circuit design,the realization of software,and the system testing.For communication protocol,the author studies the CAN trunk and J1939 protocol in depth,and designs a suitable diagnosis protocol for Baojun battery electric vehicle through the study on J1939 application protocol and Baojun E100 battery parameter by referencing its actual parameter.This diagnosis protocol consists of the physical layer,network layer,data link layer and application layer,and it is applied to design the format of fault code and CAN message.For hardware circuit design,this paper designs an overall hardware design scheme for failure monitoring system and selects the microprocessor STM32F103ZET6 with 32-bit ARM Cortex-M3 as the development platform of the system.The author designs multipath circuit for the battery power to supply dependent power to the smallest system of the battery monitoring system and the peripheral module,and carries out fault-tolerance processing on the parts to eliminate their underpower problem.The system applies TJA1050 as the receiver of CAN,builds up CAN interface circuit,and chooses TFTLCD as fault display to realize the real-time display of fault message.The failure warning module chooses buzzer with power equipment to send out alerting signal.The system applies SD storage card with 8G to store fault information and builds up corresponding peripheral circuit.On the aspect of software,this study integrally designs the software of the battery monitoring system.The design of the software of CAN communication module includes the design of CAN interrupt and the monitoring on data,and then transform the data stream in CAN trunk into physical quantity.The criteria designed in this paper is used to calculate the probability of fault occurrence,rank the level of fault severity.The system will apply different controlling countermeasures according to the severity of specific fault,read the fault information in memory area to diagnose specific fault.In the fault display module,it will display the specific fault and the severity level on the LCD screen,then the storage module can store these information into SD card to help future studies on battery fault.In the system testing stage,according to the application needs of Baojun battery electric vehicle and the calculation of data flow through fuzzy fault tree diagnostic,this study finds the fuzzy probability of battery malfunction based on the low event cut-off ?.The system can send out the fault information of the battery in the form of broadcast after stimulating the network node of battery electric vehicle with the help of CANTest and CANPro protocol analysis platform,then display the specific severity level in the failure monitoring system through the transmission in CAN trunk,and finally testifies the reliability and validity of its data through carrying out repeated stimulation testing on the developed battery monitoring system.