State of charge estimation
AIM
To estimate the State of charge
OBJECTIVES
1.Simulate the 3 test casers from harness dashboard and write a detailed report on the results.
2.What is columb counting? Refer to the above model and explain how BMS implements colomb ounting for SOC estimation?
EXPLANATION
1.Simulate the 3 test cases from harness dashboard and write a detailed report on the results.
Answer-
After the BMS closed loop dashboard model file open:-
Case1-
By clicking on BMS Sequence we get the chart
When Simulation will start in this model then all lights arere blowing green it means it is in driving condition
Result
The input cycle can be seen in the BMS_State setting when the vehicle starts driving, then charging up to SOC = 90% again and later in the standby mode. During charging the voltage of the battery pack increases to 4.2V. The cell phone temperature rises during the driving and charging cycles and begins to fall into standby mode. SOC drops to less than 50% after the driving cycle and is later charged until SOC reaches 100%. The current provided by the EV during the driving phase can be seen in the current structure.
Case2-
Now the BMS case 2 state after model driving
The driving stage 0 to 10000.
Result-
The result show the various parameter for the driving 0 to 1000. For the condition soc not increase for the charging phase.
Case3-
After applying the slected case 3 hen the no error show in dashboard.
This condition run 0 to 20000.
Result-
The result is showing the SOC increase from 80 to 100% and the reamin the standard mode.
2.What is columb counting?Refer to the above model and explain how BMS implements colomb ounting for SOC estimation?
Answer-
Columb 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 method is done to estimate the SOC, which is estimated from the discharging current, I batt, and previously estimated SOC values, SOC0
Modified columb counting method:-
To improve the Coulomb calculation method, a new Coulomb calculation method is proposed.The adjusted Coulomb calculation method uses modern adjustment to improve measurement accuracy.The adjusted current is a power charge function. There is a quadratic relationship between the fixed current and charging battery. By performing test data, currently adjusted is calculated by the following form
K1 & k2 are constant value from the experimental data.
The coulomb counting equation.
How BMS implements coulomb counting for SOC estimation
BMS Model-
Majority of electric vehicles depend on batteries that require a Battery Management System (BMS). Increasing accuracy of State of charge (SoC) estimation was crucial. The uncomplicated method for SoC estimation is Coulomb Counting (CC), however it has drawback in information of previous SoC initial value and tolerate with error propagation. Dynamic model equipped with integral controller can increase accuracy of the CC method. In this paper adjusted gain of the integral controller is proposed to further improve performance of SOC estimation. The Li-ion battery was modelled using first order RC battery model. Least square method is used to determine parameter of battery model.
BMS ECU-
The BMS ECU receives two BMS_Input inputs which are feedback from the plant model and TheStatus Application is from the state machine. This output output as BMS output and information you need to calculate current power limit on regional machine, SOC measurement and cell balance as below:-
By clicking on the soc block and we will get.
After clicking on the coulomb calculation block and we get:-
i.This system calculates the Coulomb calculator above.
ii. The advantage of the Coulomb calculation method is its simplicity and low calculation costs.
iii. Temperature and battery power are provided as inputs.
iv.The current signal is given a gain block and the temperature is given a volume as the temperature changes.
v. This input is provided for merging where the most recent with respect to time will be compiled.
vi.This output is passed to another block where it is separated by volume.
vii.SOC is therefore limited.