Research Of Battery Monitoring System For Electric Vehicle Based On FlexRay Bus

This thesis is designed to use FlexRay bus monitor battery status information platform,the lead-acid battery in electric vehicles is experimental subject.FlexRay bus is based on a flexible time division multiplex access(FTDMA)deterministic access method,it has fault tolerant and determined communication message transmission time,also it supports event-triggered and time-triggered communication ability with high speed.Compared with traditional CAN bus,LIN bus and other bus,FlexRay bus has obvious advantages.As these outstanding characteristics,FlexRay bus can be applied to satisfy a high transfer rate,high real-time performance and high-security systems,such as remote control systems,brake systems,engine control systems and other occasions.Firstly,this thesis analyzes the FlexRay bus communication protocol in detail,after understanding the present situation at home and abroad,FlexRay bus real-time,fault torrent was analyzed.And battery management system(BMS)also launched analysis,synthesis of various battery State of Charge estimation algorithm,this thesis uses the Kalman filter to calculate the SOC real value.Secondly,designed FlexRay bus communication platform,it mainly include hardware FlexRay network designing and software programming.In the hardware node designing used Freescale micro-controllers MC9S12XF512 and TJA1080 transceiver,software programming platform is used by Code Warrior.Then,designed the parameter acquisition of lead-acid battery,primarily to detect the battery voltage,current,temperature parameters.The obtained data are analyzed to detect using the Kalman filter estimation method to obtain a battery SOC changes.Finally,the status of all parameters via FlexRay bus transfer to the host controller and the host computer,in order to achieve the electric vehicle battery status information in real time.Finally,After the system platform built,using software simulation and physical tests to verify the system analysis.Simulation is used of CANoe.FlexRay to monitor bus data over transmission.Physical tests are running the entire system,discharging battery,acquiring parameters,then PC showing the monitored object status information.Through several experiments tested,and from the bus valid data frame transmission rate and delay time to analyze network performance characteristics of FlexRay bus.The analysis showed that:FlexRay bus has the message deterministic,real-time,high-speed transmission rate characteristics.By analyzing these studies,it shows the FlexRay bus has outstanding advantages compared with other conventional cars bus.