Week 7 State of charge estimation

1.Simulate the 3 test cases from harness dashboard and write a detailed report on the results

Now,at first we have to simulate 3 test cases from harness dashboard. We need to, select the harness dashboard from project file which we downloaded with the reference link https://in.mathworks.com/matlabcentral/fileexchange/72865-design-and-test-lithium-ion-battery management-algorithms. The battery model harness dash board is represented below.

When simulation will start, the model will be in driving 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

From the plot we can see the vehicle is initially in driving state and charging was done till 90%. After charging it reaches to standby mode. It can be seen in BMS state plot.Batteryemperature increases in driving and charging. Battery voltage was increased to 4.2V while charging. Current plot shows the value of current supplied to vehicle while driving. SOC decreased up to 50% in driving condition and it was increased while charging.

2) Now change the test sequence varient in case two.

RESULT:

From the above graph, a fault condition occured in second case. So even after charging was started, the soc didnt increase it continue to decrease.

3) Now by changing the test Sequence Value to 3

RESULT:

• Here we can see that the soc reached 100% in charging and remained in stand by mode. Cell temperature also decrased when standby 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 ?

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 method is done to estimate the, which is estimated from the discharging current., and previously estimated SOC values, SOC is calculated by the following equation:

SOC (t) = SOC (t-1) + At.

But there are several factors that affect the accuracy of Coulomb counting method including temperature, battery history, discharge current,

and cycle life.

Modified Coulomb Counting Method

To improve the Coulomb counting method, a new technique called modified Coulomb counting method is proposed. The modified Coulomb counting method uses the corrected current to improve the accuracy of estimation.

The corrected current is the function of discharging current. There is a quadratic relationship between the corrected current and discharging current of battery. By practice of experimental data, corrected current is calculated by the following form:

I, (t) = k₂I(t)² + k, I (t) + ko.

where ka, k, and kare constant values obtained from the practice expenmental data. In modified Coulomb counting method, SOC is calculated by the following equation:

SOC (t) = SOC (t-1) + Art.

The experimental results show that the accuracy of the modified Coulomb counting method is superior to the conventional Coulomb counting method

But there are several factors that affect the accuracy of Coulomb counting method including temperature, battery history discharge current,

ECU get the subsystem

by clicking SOC estimation we get