Week 7 State of charge estimation
1.Simulate the 3 test cases from harness dashboard and write a detailed report on the results
To simulate the 3 test cases from the harness dashbord first we have to download the file from the below given link
https://in.mathworks.com/matlabcentral/fileexchange/72865-design-and-test-lithium-ion-battery-management-algorithms and after extracting it then we have to ope in matlab and after that we have to open the test folder and chosse the BMS model.
Then the below model will be opened
Click on the test sequence block it contain 3 test sequence and first we will choose the test case1 and will run it
Then clicking on BMS test sequence and the below figure will be opened
After clicking on the TestSequence1 below figure will be opened.
The below curve shows the different parameters of the TestSequence 1
From the above curve we can see that the input cycle can be senn in the BMS_State plot in which the vehicle initially undergoes driiving the charging till SOC = 90% and then later in standby state.During the charing the battery pack voltage is increased upto 4.2V.The cell temperature increases during the driving and charging cycle and starts falling off in standby mode.The SOC drops to less than 50% after the driving cycle and then later put into charging until SOC reaches 100%.
TEST CASE 2
Clicking on the test sequence block it contain 3 test sequence and first we will choose the test case2 and will running it.
Then clicking on the BMS_Test Sequence the below window will popup
Then clicking on the TestSequence2 below window will come
The below curve shows the different parameters of the TestSequence 2
After 10,000 sec as the driving cycle ends the fault condition occures and then even in charging phase the SOC don't increases.
TEST SEQUENCE 3
Click on the test sequence block it contain 3 test sequence and first we will choose the test case3 and will run it
The above curve shows that the SOC increases from 80% to 100% and then remain in standby mode.
2.What is coulomb counting? Refer to the above model and explain how BMS implements coulomb counting for SOC estimation ?
The state of charge of a battery is important aspect of the electric vehicle .The one of the simple and easy method of counting the SOC is coulombscounting method. In coulombs counting method the discharging current of the battery is measured and after its measurement it is integrated over time in order to estimate SOC.The formula for calculating involves the addition of previous claculated SOC value SOC(t-1) and integrated value of current over time I(t).
In this method the current is to be calculated precisely as it can creat error in calculation of SOC. Other factors such as temperature, battery history, initial SOC and cycle life also influence the precision of the SOC estimate.
Clicking on the BMS ECU we get below figure
The below figure is the SOC estimation unit
After clicking on the SOC estimation unit we get below figure.
From the above figure we can see the Coulombs counting block
After clicking on it we get the below figure.
The above figures show hoe the SOC is calculated .