| Environmental pollution and energy shortages are the mainly factors to restrict thedevelopment of the traditional automobile,electric vehicles attract the attention of the socialincreasingly with the advantages such as zero emission,using renewable energy,and theenergy can be recycled while braking in the process of use.Power battery is the only energysource of the pure electric vehicle,and the development of the electric vehicle is impossiblewithout the performance support of the power battery,so the mainly duty of the batterymanagement system(BMS) is to keep the power battery working in the best state as much aspossible.The state of charge(SOC) reflect the energy of the battery that can be used, Theforecast of SOC is the mainly task of the BMS system.Because the value of the SOC is veryimportant to the whole system,so it is necessary to promoting the accuracy of the value of theSOC.While in the design of the whole system,12slaver acquisition module and1mastercontrol module communicated with each other based on the help of topology of CANnetwork.Slaver acquisition module mainly used to pick the voltage and temperature of thebattery,and then transmit the message to the master control module in the help of CANbus.Besides,the thesis also gave a circuit design to protect battery from over current based thePACK technology.While the slaver acquisition module picking the voltage of monomerbattery,according the time and order to pick the data one by one,then compare the measuredvalue with the real value,finally calibrated the new measured value by the difference betweenthe older measured value and real value,which can make sure the measured value close to thereal value as soon as possible with the closed loop structure calculate method,of coursepromoted the accuracy of the measured value of the voltage.While estimating the value of SOC,has compared several traditional estimate method,thethesis also gave a strategy based the actual situation,which combined open circuit voltage method and ampere-hour integration method,besides,the capacity of the correction factor wasadded also to adjust the estimated results.A algorithm called “optimized algorithm†waspresented in order to calculate the correction factor.The result of the laboratory test provedthat the method can keep the estimated error under5%under certain conditions,and has nostrict requirement for the model and MCU.Finally the thesis has presented an estimationstrategy of the remaining mileage combined with the vehicle parameters and the trafficconditions,and also gained the simulation results of the vehicle performance in the use ofCruise. |
