Research And Design Of The Monitoring And Management System On New Energy Lithium Ion Battery

In today,s society,energy depletion,air pollution,and global temperature rise are related to the petroleum-based fossil energy crisis.Lithium-ion batteries is green and pollution-free new energy sources that can be used repeatedly,which is consistent with the sustainable development concept of China's new energy development and utilization.Based on the inconsistent characteristics of the single cells in the lithium-ion battery pack,the BMS(Battery Management System)is required to monitor the battery effectively during charging and discharging.Compared with foreign countries,the domestic BMS technology level is different.There are some differences in the reliability and accuracy of critical information such as battery pack life and battery life.The efficiency of battery is reduced,the service life is shortened,and the best performance of the battery don't being exerted fully.Based on main controller STM32F103RCT6 and power management chip bq76940,a new energy lithium-ion battery monitoring and management system is built for the application of lithium-ion battery in the field of small electric vehicles in this paper.In the paper,52-cell nominal 48 V lithium batteries that is connected in series with 13 string of batteries that is connected in parallel with 4 batteries is the managed object.The overall design scheme and SOC estimation method of lithium ion battery monitoring and management system are proposed.Hardware and software design of lithium ion battery monitoring and management system is completed.The hardware is based.on the main controller STM32F103RCT6,which communicates with the power management chip bq76940 and PC host computer through IIC and serial port respectively.The design based on the bq76940 of the chargeing and dischargeing equalization circuit,the battery overcurrent short circuit protection circuit,and temperature monitoring and management circuit,voltage and current acquisition circuit,etc is completed.The software based on Kei15 and QT is designed including data acquisition,temperature detection management,overcurrent short circuit protection,charging and discharging balance protection,SOC estimation and lithium ion battery monitoring and management user interface,etc.The datas of voltage,current and temperature of the battery pack can be abtained.The related parameters can be set,such as equalization voltage accuracy,overvoltage and undervoltage.The functions of the software and hardware was debugged and verification.The testing experiment was done on the platform.In the voltage sampling experiment,the absolute error of voltage is only 12mV,and the relative error is only 0.32%.The highest charging voltage is basically at the nominal level of 3.7 V,and the discharging is basically reduced to cut-off voltage 2.75V in the equilibrium protection experiment.In the SOC estimation experiment,the displaying data is in accodance with the actual accident situation.The system is stable in operation.The objective problems were improved,such as overcharging or overdischarging due to the inconsistency of the single cells in the battery pack.The system is suitable to use in the field of small electric vehicles.