| Real-time and accurate state estimation of Lithium-ion power battery is related to its reasonable use in electric vehicles(EVs).In view of the Lithium-ion battery is a time-varying,dynamic,strongly nonlinear system,the uncertainty caused by many factors such as degradation,external environment and the working operations makes it a great challenge for a battery management system(BMS)to accurately estimate battery state when the Lithium-ion battery is commonly employed in EVs.The research solves the application problem of Lithium-ion batteries for EVs.Some work is studied with respect to the degradation electrochemical mechanisms of Lithium-ion battery and single electrode mechanism modeling,electrochemical mechanism-electrical coupling modeling theory of Lithium-ion battery and combined SOC/SOH estimation methods based on models.The detailed research work is as follows:1)On the degradation electrochemical mechanisms of Lithium-ion battery and single electrode mechanism modeling,the research solves the problem of performance degradation for Lithium-ion batteries in operation.Methods of electrochemical mechanisms for Lithium-ion batteries have been studied from macro-micro scale.The mapping relation between battery degradation and loss of cycleable lithium and active material is discussed.Furthermore,a detailed post-mortem analysis is carried out by using high resolution imaging microscopy.The evolution of stress and strain energy due to diffusion induced stresses(DISs)during the repeated lithium insertion/extraction processes into/from electrode particles is validated by experiment.The important role of the evolution of phase structure and morphology evolution caused by reversible electrochemical insertion/extraction of Lithium-ions in the active materials in the process of battery failure is determined.Based on the above research,the mapping relation between battery SOC and surface Lithium-ion concentration of single electrode,and the battery SOH and battery internal resistence are proposed in this study,which provides a research basis for the battery accurate modeling and SOC/SOH estimation subsequently.2)On the order-reduced electrochemical mechanism-electrical coupling modeling for the Lithium-ion batteries,On the order-reduced electrochemical mechanism-electrical coupling modeling for the Lithium-ion batteries,the research solves the application problem of electrochemical mechanism-electrical coupling model in BMSs for real EVs.Based on the electrode dynamics theory and law of conservation of charge and ion,the order-reduced electrochemical mechanism-electrical coupling models with clear physical meanings and simple structure are built by adopting finite fifference method,finite volume method and homogenization method through assuming that the Lithium-ion concentration and the current density are constant.The proposed order-reduced electrochemical mechanism-electrical coupling model not only reduces computation,but also guaranteed the enough precision.It can be used for accurate modeling of power battery life cycle and complex operating conditions in EVs.3)On the combined estimation of SOC/SOH for Lithium-ion battery electrochemical mechanism-electrical coupling model,the research solves the problem of online state estimation for electrochemical mechanism-electrical coupling model under dynamic performance test procedure.Battery state equation of the order-reduced electrochemical mechanism-electrical coupling model is established by employing time-frequency transformation and numerical methods.Combined with SOC and SOH decouping method,battery state estimation algorithms based on the inproved order-reduced models are developed by adopting and sliding-mode observer and extended kalman filter.In the case of accurate battery SOC initial value,the SOC/SOH joint estimation is realized by using these algorithms under HPPC operating conditions.Comparison of the simulation results and the experimental data is performed to verify the accuracy of the simulation results.4)On the combined estimation of SOC/SOH of Lithium-ion battery electrochemical mechanism-electrical coupling model using an urban driving schedule,the research solves the problem of battery combined SOC/SOH estimation for application in BMSs for real electrical vehicles because of the large calculation amount of the electrochemical mechanism-electrical coupling model.Battery dynamic testing condition based on the statistical urban driving schedule is introduced and established.Then,order-reduced electrochemical mechanism-electrical coupling model based methods are proposed.A combined SOC/SOH estimation is performed under battery dynamic testing condition with incorrect initial values of SOC.Furthermore,Lithium-ion battery test is proposed to verify and evaluate the achieved estimation performance for the estimation methods under incorrect initial SOC value.It solves the problem of accurate joint SOC/SOH estimation for battery electrochemical mechanism-electrical coupling models using the urban driving schedule.Thus,to solve the problem of combined battery SOC/SOH estimation of electrochemical mechanism-electrical coupling model and provide a theoretical support for the efficient application in EVs,this research has proposed an degradation electrochemical mechanisms research methods of Lithium-ion battery and single electrode mechanism modeling,electrochemical mechanism-electrical coupling modeling theory of Lithium-ion battery and combined SOC/SOH estimation methods based on order-reduced electrochemical mechanism-electrical coupling model using an urban driving schedule for EVs.To solve the problem of combined SOC/SOH estimation for Lithium-ion battery electrochemical mechanism-electrical coupling model for vehicle application,some order-reduced electrochemical mechanism-electrical coupling model based estimation methods have been proposed. |
