Week 7 State of charge estimation

1.Simulation of 3 test cases :

BMS_closed loop Harness Dashboard,

Selecting the test case : 1

First 3000 sec the cell balancing takes place, and after 1000 seconds it will be in charging and balancing state and

next 5000 seconds it will be in post charge balancing mode.

Simulation after 20000 seconds,

Light blocks turns green as there is no fault in model.

It can be observed from the plot that the vehicle is initially in the driving state and charging was done till 90%. After the charging mode it reaches to the standby mode which can be seen from the BMS state plot. From the Cell temperatures plot it is observed that the battery temperature rises in driving and charging.

Selecting the test case : 2

First 10000 sec the model is in charging state.

It was observed from the plot that the battery discharges completely in 8692 seconds and the vehicle does not go forward and the charging state was not achieved at 10000 seconds. Hence the vehicle comes to standby condition and simulation stops midway.

It is just the continuous charging condition from the start till the end of 20000 seconds of simulation.

2. 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 method is done to estimate the SOC(t), which is estimated from the discharging current, I(t), and previously estimated SOC values, SOC(t-1).

BMS Closed Loop model :

Current signal is given to the gain block and the temperature is given to capacity as it varies according to the temperature. These inputs are given to integration where current will be integrated wrt time. This output is given to another block where it is divided by capacity and henceforth the SOC is estimated.

Conclusion:

The 3 test cases from harness dashboard were simulated and discussed successfully along with the coulomb counting done by BMS for SOC estimation.