Development Of Battery Pack Management System For Power Integrated Power System

The power integrated power system integrates the traditional power system power equipment to control the power system,and shares a set of battery sets.Valve regulated lead acid battery is widely used in traditional power supply system,but the energy density of VRLA is low and the environmental pollution is serious.Due to its high energy density and environmental friendliness,lithium battery is gradually replacing valve regulated lead-acid battery in integrated power supply system.At present,the combustion accidents of lithium batteries are mainly caused by thermal runaway and the battery management system lacks thermal runaway warning function,so lithium batteries have high security risks in use.In this paper,aiming at the problem of poor performance and lack of thermal runaway alarm of battery management system,a battery management system with high performance and high security is designed.At first,this paper analyzes the characteristics,working principle and thermal runaway mechanism of lithium battery.By comparing different battery equivalent models,the second-order RC equivalent model is selected as the equivalent model of lithium battery and then identify the model parameters.In this design,the unscented Kalman filter algorithm is improved and the square root algorithm is added to form the improved square-root unscented Kalman filter algorithm to estimate the state of charge of battery.In the MATLAB simulation environment,the accuracy of the equivalent model and SOC algorithm is verified.Secondly,according to the master-slave topology,the battery management system is divided into master control module and slave control module.S32K144 is selected as the control chip of the main control module,and the hardware circuits of power supply,data storage,USB communication and real-time clock are designed.In the main control module,the hardware circuit of wireless communication chip ESP8266 is designed to realize the function of connecting WLAN and server communication.The S9KZEAZ128 was chosen as the control chip of slave control unit,and MC33771 was chosen to be the battery monitoring chip.The circuit of single voltage acquisition,temperature detection,battery equalization and can communication are designed.After the completion of the hardware circuit design,write the software program of the corresponding functional modules.To realize the fast and reliable update function of the program,the bootloader program is designed in the main control module.As for the problem of thermal runaway,the thermal runaway alarm program is designed.Finally,the battery management system is made,and a test platform is built for functional test.And the test results show that the current acquisition error of battery management system? ± 1%;temperature error ? ± 1?;Acquisition error of cell voltage ? ± 3mV;SOC estimation error is less than 4%;The battery equalization function can control the maximum voltage difference within 50 mV;The thermal runaway alarm function can quickly find the thermal runaway problems and distinguish the types;The fault diagnosis function can find the abnormal state in time;Bootloader function can update the main control program quickly and reliably;The wireless communication module can stably send the data of battery management system to the server.Through the physical test,it is proved that the design can realize the monitoring function of the battery pack in the integrated power supply system,and meet the design requirements.