Research On SOC Estimation Of On-Board Spare Lead Acid Batteries In Rail Transit

In recent years,with the rapid development of China’s rail transit,more and more attention has been paid to the safe operation of rail transit.In rail transit,vehicle-mounted battery is an important standby power supply equipment.It is the last line of defense for driving safety when the external power supply fails and acts as a "pacemaker".The operation and mainte nance status of the standby battery is directly related to the safe operation of the vehicle.With the development of Internet big data,obtaining various monitoring data of battery status is the prerequisite for realizing intelligent battery operation and maintenance.In this paper,based on a high and new technology industry in hunan pr ovince science and technology innovation plan lead project "rail transit on-board battery ops chip,algorithms and intelligent cloud management system research and development",considering the characteristics of rail transit spare batteries,lead-acid battery as the research object,based on the current backup battery SOC estimation rarely consider the problem of floating state,Tested from floating state began to discharge the battery discharge capacity under different conditions,studied the battery SOC estimation,design the software and hardware,realizing the function of SOC estimation and the accuracy of SOC estimation scheme is verified by experiment,for subsequent upload battery monitoring data to the cloud platform,for big data analysis provides the basis for further research.This paper first analyzes the power s upply conditions of rail transit standby battery and the energy flow direction in case of failure and power outage,explains th e working principle and performance parameters of the batter y,and obtains the variation of battery available capacity at different discharge rates and different discharge temperatures.Secondly,analyze the deficiency of the traditional ampere-hour integral method,considering the limited use of Peukert equation,using th e concept of effective current,the discharge ratio and temperature on the influence of battery capacity conversion on the effective current,reducing the discharge ratio and temperature on the SOC estimation error,combined with correction strategy and st rategy of aging correction auxiliary charging process,Ensure the consistency of the charged battery amount and correct when the battery capacity is aging.Then,in order to realize the function of SOC estimation,the main contro l circuit,current and voltage sampling circuit and communication circuit are designed,and the corresponding program software is designed to complete the functional system of SOC estimation.Finally,an experimental platform for battery testing was set up,and the SOC was tested in the main working condition when the battery was charged down and the temperature changed before and after the floating charge state.The capacity correction ability of several charge and discharge cycles was verified.The results show that the SOC estimation errors have good accuracy.The hardware circuit of SOC estimation is also tested and its function is good.