Week 7 State of charge estimation
1.Simulate the 3 test cases from harness dashboard and write a detailed report on the results
2.What is coulomb counting? Refer to the above model and explain how BMS implements coulomb counting for SOC estimation ?
SOLUCTION:
NOW WE HAVE TO Simulate the 3 test cases from harness dashboarD.WE HAVE SELECT THE HARNESS DASHBOARD FROM PROJECT FILE WHICH WE HAVE DOWNLOAD THE REFERENCE FILE.https://in.mathworks.com/matlabcentral/fileexchange/72865-design-and-test-lithium-ion-battery-management-algorithms
THE BATTERY MODEL REPRESENT BELLOW.
WHEN SIMULATION WILL START THE MODEL WILL BE IN SRIVING CONDITION.AFTER 3000 SECONDS IT WILL BE IN STANDBY MODE AND AFTER 1000 SECONDS IT WILL BE IN CHARGING MODE NOW BY RUNNING THE SIMULATION.
RESULT:
HERE ALL THE INDICATORS ARE GREEN SO WE CAN SEE NO ERRORS AND WE CHECK THE PLOT FOR THIS MODEL AND IS SHOWN BELOW.
2)NOW CHANGE THE TEST SEQUENCE VARIENT IN CASE TWO.
NOW CLICK ON BMS STATEMENT BLOCK.
THE DRIVING STAGE IS FOR 0 TO 10000 SECONDS.THEN CHARGING STAGE OCCUR
RESULT:
3.now changining the test sequence value to 3
this condition has only one phase and that is chargining thus 0 to 20000 seconds simulactions runs.
results:
here we can see that the soc reached 100%in charging and remained in stand by mode. cell temperature also decrased when stsndby mode was acheived.
from the 3 cases we observer that only charging takes place thus soc was 80%at first then soc increases to 100%in 2000 seconds then soc remains constant at 100%.
2.What is coulomb counting? Refer to the above model and explain how BMS implements coulomb counting for SOC estimation ?
coulomb counting:
the coulomb counting method measures the discharging current of a battery and integrates the discharging current over time in order to estimate soc.coulomb counting methods is done to estimate the which is estimated from the discharging current. and previously estimated soc values.soc is caluclated by following equation.
but there are several factors that affect the accuracy of coulomb counting method inculding temperature,battery history,discharge current,and cycle life.
modified coulomb couting method
for example we can look into the project file we download.a bms system in the file is represented below.
BMS ALGORITHM MODELS,PROTECTS THE MEASUREMENT FROM BATTERY PACK.
BY CLICKING ON THE BMS ECU WE GET THE SUBSYSTEM.
BY CLICKING SOC BLOCK WE GET.
FROM ABOVE FIGER WE OBSERVE COULOMB COUNTING.
A SUBSYSTEM OPEN WE CAN CLICK ON A COULOMB COUNTING.
1.THE SYSTEM DOES THE ESTIMATION BY COULOMB COUNTING EQUATION MENTIONED ABOVE.
2.ADVANTAGE OF COULOMB COUNTING METHOD IS SIMPLICITY AND LOW COMPUTIONAL COST.
3.TEMPERATURE AND CURRENT FROM THE BATTERY IS GIVEN AS INPUTS.
4.CURRENT SIGNALS IS GIVEN TO A GAIN BLOCK AND TEMPERATURE IS GIVEN TO CAPACITY SINCE IT VARIES ACCORDING TO TEMPERATURE.
5.THIS OUTPUT IS GIVEN TO ANOTHER BLOCK WHERE IS DIVIDED BY CAPACITY.
6.HENCE THE SOC IS ESTIMATED.
THE-END