Research And Design Of Lead-acid Battery Charger

In order to deal with the depletion of traditional energy such as oil and reduce the pollution to the environment.New energy is more and more advocated by people,and the development of new energy has become a global theme.New energy batteries,as energy storage tools,are used on all sides of life,factories,cars and even high-speed rail began to use batteries to provide energy.After the battery is used on a large scale,there are also many problems.This paper improves the traditional charger of lead-acid battery,provides maintenance to the battery,and carries on the charging control after collecting the voltage and current of the battery.It not only improves the charging efficiency but also delays the service life of the battery.The main research contents of this paper are as follows:(1)The electrochemical principle of internal charging and discharging of leadacid battery is analyzed,and the charging characteristics of lead-acid battery are analyzed.(2)The common charging methods of lead-acid battery are studied.Combined with various charging methods and charging characteristics of lead-acid battery,a fivestage charging method is designed,including pulse charging,activation charging,constant current charging and constant voltage charging,floating charging.Pulse charging can remove sulfur to repair the battery,and floating charging can effectively avoid the problem of battery overcharge and insufficient charging power.A seriesparallel charging method is designed for four batteries.(3)Several common battery SOC estimation methods are studied,the relationship between battery parameters and battery SOC is analyzed,and the initial SOC value of battery is determined.The composite model of the battery is established,and the extended Kalman filter method of the composite model is used to estimate the battery SOC.(4)According to the functional requirements,the hardware circuit of the charging system is designed,and the input filter circuit,half-bridge converter,high frequency transformer,PWM control circuit,sampling circuit and so on are studied.According to each module of charging system,the function of the system is designed,and the charging control strategy is realized.(5)The output PWM waveform of single chip microcomputer,the output waveform of photocoupler and the output waveform of driving chip are tested,and each waveform meets the requirements.The SOC estimation method of battery is tested.the estimated SOC value can be quickly close to the actual value,and the error can be controlled within 4%.The actual charging effect of the charger is tested,and the charging time and battery charge meet the requirements.