Lead-acid Battery Charge And Discharge Monitoring And Control System

The unreasonable charging and discharging made the capacity of the lead-acid battery drop rapidly and shorten the service life,this woud affect the security of the lead-acid battery as a power supply.To solve the problem,a charge and discharge monitoring and control system for the lead-acid battery was designed in this paper based on the charge and discharge characteristics of the lead-acid battery.The main contents of the paper are as follows:(1)The main factors that will affect the service life of the lead-acid battery were determined through the analysis of the charge and discharge characteristics of the lead-acid battery.The main factors were as follows: overcharge,over discharge,ambient temperature,long-term floating charge and the unbalanced of the individual battery in the serial lead-acid battery pack.(2)The design of the circuit for charge and discharge monitoring was completed.A series of circuits were designed based on STM32 microcontroller as the main control chip,including the charge and discharge current detection circuit for the serial lead-acid battery pack,the voltage and temperature detection circuit for the individual battery in the serial lead-acid battery pack,the communication circuit and the auxiliary power supply circuit.To ensure the security of the system,linear optocoupler HCNR201 was used to achieve voltage isolation detection,and current sensor ACS712 was used to achieve current isolation detection.(3)The design of the circuit for charge and discharge control was completed.The design of the discharge isolation control circuit of the lead-acid battery pack was completed,and the design of the charging voltage isolation control circuit based on the Buck circuit was completed by using the optocoupler and MOS transistor driver IRS21850 S.(4)The software design for the system was completed.The software design for the system function modules and the entire system was completed to achieve the charge and discharge status monitoring for the lead-acid battery pack.The discharge control,the temperature compensation control for the charging voltage and the balanced control during the charging were realized according to the monitoring data.(5)Testing and analysis for the system were completed.The whole system was built,the function modules and the whole system were tested and analyzed,and the error was corrected.The test results demonstrated that the voltage detection accuracy for the serial lead-acid battery pack could reach ±100mV,the voltage detection accuracy for the individual battery could reach ±50mV,the error of the current detection was less than 2%,the temperature compensation control for the charging voltage and the balanced control during the charging could be realizhed in the lead-acid battery monitoring and control system.The system could monitor and control the charge and discharge of the lead-acid battery effectively.