Research And Development On Energy Storage Battery Management System

With the rapid development of society,solar energy as a new type,green renewable energy has been paid more and more attention.Photovoltaic power generation system is becoming more and more known and technology is becoming more and more mature under the support and subsidies of the country.Although solar energy is widely distributed and pollution-free,it is limited by many environmental and regional factors.Therefore,it is necessary to store the electric energy in the PV power generation system,when the energy stored in the storage device can continue to supply power to the load,and the energy can be stored when there is no load or the power generation is surplus.In this paper,based on the household independent photovoltaic discharge system,a battery charge and discharge management system with the functions of battery charging,discharging,automatic charge-discharge switching and state of charge of charge and discharge(SOC)estimation is built.The charging and discharging methods and charge-discharge circuits of batteries are analyzed and compared.The second order RC equivalent circuit battery model and the charge/ discharge system small signal model are established.On the basis of the model,the battery charging and discharging are studied.Charge / discharge switching control algorithm and battery residual quantity estimation method are verified by simulation and experiments.The specific research contents are as follows:Taking lead-acid battery as the research object,the model of the equivalent circuit of the battery is established to identify the model parameters and verify the simulation.The charging and discharging method and the circuit of charge and discharge of the battery are studied.The charging and discharging methods and the main circuit topology of the battery are selected,the principle of thecharging and discharging circuit is analyzed in detail,the control variables of the system are selected,and the state space models in charge mode and discharge mode are established respectively.The battery charging and discharging controller based on Pi control is studied and designed.The charging controller adopts the control structure of single and double closed loop,the constant current charging is realized by current single closed loop control,the constant voltage current limit charging is realized by double closed loop control of voltage and current,and the discharge control adopts double closed loop control structure.The voltage outer loop is used to stabilize the bus voltage,and the current inner loop is used to limit the battery discharge current.The simulation results show that the control method is effective,but during the charging process,the charging current is too large,the steady-state precision is low,and the charging current regulation time is long in the process of dynamic switching.Startup time occurs during discharge The problem of long and dynamic adjustment speed is too slow.Aiming at the problem that Pi control method is difficult to make battery charge and discharge system have better steady and dynamic performance,a battery charge and discharge control method based on current predictive control is designed.On the basis of Pi double closed loop control,the current predictive controller is used to replace the current inner loop,which realizes the optimization and improvement of the control algorithm.On the basis of the improved charging and discharge control algorithm,the battery charge and discharge switching controller is designed.Through theoretical analysis and simulation verification,it can be seen that the improved control method can realize the charging and discharging functions of the battery,eliminate the charge current shock during charging start-up,and achieve steady state accuracy of constant current charging.In the constant current constant voltage switching process,seamless switching is realized,the starting time of the bus voltage reaches a given value rapidly during discharging,the dynamic response time is shortened in the loading and cutting process,and the steady state performance and the dynamic performance of the charge and discharge system are improved.A battery SOC estimation method based on RLS and complementary filter is proposed.First,we improve the Ann time integration method to eliminate the accumulative estimation error,secondly,further eliminate the estimation noise by complementary filter,and finally use the RLS algorithm to identify the estimated model parameters online to improve the dynamic of the estimation system.The theoretical analysis and simulation results show that the proposed SOC estimation method can realize the SOC estimation of the battery,and the estimation error is small and the estimation accuracy is high.The experimental results show that the charging and discharging control method based on current predictive control has strong steady-state and dynamic performance.The method of battery SOC estimation based on RLS and complementary filter has high estimation accuracy.