Joint Estimation Of SOC And SOH For Lithium-ion Batteries In Vehicles Based On Multi-time Scales

In view of the reaction characteristics of lithium-ion ba Vehicle-borne lithium-ion batteries have become the driving units of electric vehicles because of their advantages of green,renewable and noise-free.Due to the inconsistent changes of individual batteries in vehicle-borne lithium-ion batteries,the state of Charge(SOC)and health status of battery energy management system(BMS)Estimation of ate of Health(SOH)is currently a key research issue,and strict battery management strategy is designed.In this paper,based on the multi-time scale theory,the nonlinear extended Kalman predictive filter is used as the estimation algorithm to estimate the SOC and SOH accurately.Finally,the vehicle controller and the test platform are validated and analyzed.The state estimation methods of Vehicle Lithium-ion batteries are studied and analyzed from the following aspects:1.tteries in vehicle,considering the corresponding relationship between open-circuit voltage and SOC of batteries at room temperature,the reaction characteristics of lithium-ion batteries in vehicle at different discharge rates and temperatures were studied,and the battery parameters transmitted by the upper computer of batteries were combined to establish a model considering the change of temperature effect of batteries.The second-order RC equivalent circuit model is improved and the parameters are identified.2.Aiming at the influence of complex thermal environment on lithium ion electric SOH in vehicle,the temperature and thermal influencing factors were calculated and the thermal model was established.The change of SOH was obtained by macro-scale analysis.3.Aiming at the joint evaluation method of SOC and SOH for lithium-ion batteries in vehicle under multi-time scale EKF proposed in this paper,the algorithm is designed,and the vehicle controller and test platform are developed.The algorithm is validated by compiling an estimation module with Structured Text(ST)in Programmable Logic Controller(PLC).The accuracy of the model provides an experimental basis for the energy allocation strategy of BMS for vehicle lithium ion batteries.In this paper,considering the thermal environment factors and the internal and external temperature changes of vehicle-mounted batteries,a combined estimation method of SOC and SOH for vehicle-mounted batteries based on multi-time scale EKF is proposed,and the estimation module of vehicle-mounted batteries state for vehicle controller is developed and the test platform is built,which provides theoretical basis and engineering application index for the development and utilization of vehicle-mounted batteries BMS.Guidance has a high value of innovation construction and promotion.