Design On Battery Management System Of High Power Lithium Battery Energy Storage System

As a new type of energy source,lithium battery is widely used in energy storage systems due to its strong cycle capability,large discharge current and fast charging speed.However,compared with other energy storage energy sources,battery safety is poor,battery charging and discharging process control is difficult,and it is necessary to join the battery management system to monitor and protect the lithium battery energy storage system.This paper mainly studies a battery management system for high voltage and high power lithium battery energy storage system.The battery management system monitors and protects the battery by collecting battery voltage and temperature;collects charging unit parameters and monitors the charging process in real time.The battery management system can improve the stability and safety of the lithium battery energy storage system and improve the output DC power quality of the energy storage system.Aiming at the problem of large current discharge voltage drop,temperature rise and long-term working stability of energy storage system,this paper conducted a series of cyclic experiments on lithium iron phosphate battery to investigate its high current discharge reliability,high and low temperature working stability,and determine the best work.Temperature,determine the connection method of the battery module.In order to simulate the relationship between the external characteristics of the battery and the internal state,the second-order modeling analysis of the battery cell is carried out,and the SOC estimation algorithm based on the improved ampere-time integration method is proposed to solve the problem that the traditional ampere-time integration method cannot predict the initial value of the battery SOC.The battery management system hardware circuit is designed,including the module controller and centralized controller.Aiming at the large number of battery modules in the energy storage system and the communication isolation between the controllers,this paper adopts the master-slave control mode.One centralized controller communicates with 15 module controllers through the isolated CAN communication module.The reliability and stability of the hardware system.In this paper,the battery equalization method adopts the decentralized DC-DC equalization method.The equalization charging unit adopts the PFC+ half-bridge converter to realize the AC220V-DC30 V conversion.The driving method adopts the pulse transformer drive to solve the problem of isolation between the high voltage side and the driving side of the bus.The charging mode adopts the constant current and constant voltage mode.For the traditional PI controller,the current overshoot is large and the dynamic performance is not good.This paper designs a charger controller based on predictive model control instead of the traditional current inner loop.The current dynamic performance of the charging system prevents the sudden change of the charging current from adversely affecting the battery.Finally,the battery management system software design was carried out,including the main program of the system,the voltage acquisition program based on LTC6803,the temperature acquisition program,the SPI communication program,the SOC estimation program,and the CAN communication program.The acquisition accuracy of the battery management system is tested.By comparing the collected voltage,current,and temperature with the actual value,the test results show that the battery management system software has strong reliability and high acquisition accuracy,which satisfies the requirements of the energy storage system.