Design On The Management System Of Lithium Ion Battery In Electric Vehicles

Accurate estimation of the charged state(SOC)and health state of the power battery(SOH)of electric vehicles,energy balance of single power battery and real-time monitoring of power battery operation information are of great significance to improve the efficiency of power battery,prolong its service life and daily maintenance.Based on this,the estimation of SOC and SOH,energy balance and real-time monitoring of operation information of power battery are studied.For the estimation of SOC and SOH of power battery,an estimation strategy based on fractional order double extended Kalman filter is proposed.Firstly,fractional order is introduced on the basis of integer order second order RC equivalent battery model.Through parameter identification and MATLAB simulation analysis,it is concluded that fractional order equivalent battery model has higher accuracy.Secondly,through the MATLAB software,the SOC estimated by fractional order extended Kalman filter and the SOC estimated by integer order extended Kalman filter are simulated and analyzed.It is concluded that the error of SOC estimation by fractional extended Kalman filter is smaller and more accurate.Finally,considering the influence of capacity and ohmic internal resistance on SOC estimation,the dual extended Kalman filter is introduced on the basis of fractional order extended Kalman filter,and theactual capacity is estimated to characterize SOH while SOC of power battery is estimated.Through MATLAB simulation analysis,it is concluded that the proposed estimation strategy is feasible.For energy balance and real-time monitoring of operation information,the software and hardware based on embedded system and host computer software are designed.Firstly,the software and hardware design of voltage,current,temperature and equalization circuit are introduced.Secondly,the host computer software is developed based on Visual Studio 2012.Finally,the SOC and SOH estimation strategy,cell equalization and real-time monitoring of operation information are tested and analyzed by the host computer software.Through the test and analysis of MATLAB and host computer software,it can be concluded that the strategy of power battery SOC and SOH estimation,energy balance of single battery and real-time monitoring of operation information are feasible.