The Research And Application Of The Residual Capacity Of Lead Acid Battery

Lead-acid batteries are widely used in back-up emergency power supply system and low-speed electric cars motive power supply,so timely grasp the performance parameters and the actual running condition of the battery is especially vital.State Of Charge is one of the most important parameters which describes running status of the battery showing the actual battery power capacity.Accident failure or insufficient power supply ability of battery often cause immeasurable loss,so the real-time and accurate estimation of SOC is urgently demand at home and abroad.SOC estimation is the core task of battery management system.Due to the internal electrochemistry reaction and a variety of complex factors,SOC can not be accurately estimated most of the time.The study of the residual capacity and the practical application based on accurate estimation of SOC are current research hot and difficult issues in the direction of battery,which have wide development prospects.The research respectively studies accurate SOC estimation methods suitable for backup power supply and motive power supply.It introduces the basic properties of lead-acid battery,including its working principle and state parameters,and studies characteristics and parameters change trend during battery charging and discharging process.Meanwhile it also discusses SOC estimation based on recovery voltage.This paper studies the transformation of parameters in the process of being stability after emitting a certain capacity of a battery using the method of short pulse dc discharge.By measuring the recovery voltage under different SOC and normalizing process,the relation between normalized recovery voltage and current SOC are fitted and the function equation is observed and the method of checking capacity test is compared.Influence factors of SOC estimation precision of power battery including discharge rate,aging and temperature are also studied and then motive battery SOC estimation strategy is put forward.Finally,hardware circuit and software program based on the low speed electric vehicle battery management system are designed as well as battery balance.The innovations of this paper are:1.It studies the transformation of parameters in the process of being stability after short pulse dc discharge.Normalization of recovery voltage method is proposed to eliminate the effects of inconsistent initial battery voltage to the data processing.It fits the function of normalized recovery voltage and SOC,and proves that this function has nothing to do with discharge time but discharge rate using varies experiments.Based on the above conclusion,the residual capacity of battery can be determined by short-term discharge,and SOC estimation error is less than 5%,and is more convenient,fast and save.2.In the process of researching SOC estimation methods of motive battery,a lot of actual working conditions tests are carried through,and parameters change trend of motive battery during electric car operation under complex conditions are obtained.In the SOC algorithm optimization,full consideration of actual operation of electric cars are taken.It can be divided into static parking and dynamic operating states and respectively use different algorithms to estimate SOC will make a more accurate estimation as well as more down-to-earth.