The Modeling And SOC Estimation Of MH-NI Power Battery

With the aggravation of energy crisis and the environmental problems caused by the discharge of fuel vehicles,the advantages and disadvantages of electric vehicles with their zero pollution,high efficiency and low noise have been paid more and more attention from all over the world.Ni-MH battery as a high energy than the high power,long cycle life and pollution of small energy storage equipment,in the new energy electric vehicles and hybrid electric vehicle power selection,has become one of the main choice The In this paper,nickel-hydrogen battery as the research object,to explore ways to improve the accuracy of SOC estimation.Aiming at the large influence of polarization on the open-circuit voltage of Ni-MH battery,an improved SOC estimation method based on open-circuit voltage self-tuning is proposed,and good results are obtained.Firstly,the working principle of MH-Ni battery is briefly introduced.The basic characteristics of the battery are tested by designing the experiment and the factors influencing the battery SOC are analyzed.Considering the characteristics of the battery,the first-order Thevenin model was used to establish the equivalent circuit model of the MH-Ni battery.The HPPC cycle experiment was designed.The parameters of the battery model were identified by the recursive least squares method.The battery model was established in Matlab,The feasibility of the battery model is verified by simulation,and the open circuit voltage parameter is modified.The modified model has better followability for the variable current condition test and the terminal voltage.An improved SOC estimation method based on open-circuit voltage self-tuning is proposed,which is more accurate in selecting the open-circuit voltage and improving the accuracy of the whole algorithm.The charging model parameters and the discharge model parameters were identified by HPPC experiment and discharge HPPC experiment.SOC estimation was carried out by using the extended Kalman filter algorithm for charging cycle and discharge cycle experiment.The results show that the charging model parameters are used for charging cycle experiment The accuracy of the discharge model is high,and the parameters of the two models are not high for the variable current condition.For the DST condition,the improved Kalman filter algorithm based on the open circuit voltage self-tuning is more accurate than the charging model parameters and the extended Kalman filter algorithm of the discharge model parameters.