Week 7 State of charge estimation

01)

First Test Sequence Variant 01 :

All the green lights are blowing thats mean there is no fault found.

While driving and charging the temperature is increase show in cell_Temperature Plot.

BMS State-standbymode is 0,After the charging mode it reaches to the standby mode which can be seen from the BMS state plot

First Test Sequence Variant 02 :

All the green lights are blowing thats mean there is no fault found.

The battery is discharges completely in 8690sec and car is stop and simulation is also stop.

First Test Sequence Variant 03 :

All the green lights are blowing thats mean there is no fault found.

The peak_current plot drops from 0 to 3000 sec and constant as the charge is not used anywhere the driving is not present.

02)

Coulomb Counting Method :

Coulomb counting method is a type of book-keeping estimation method that uses battery discharging current data as input. This method permits to include some internal battery effects as self-discharge, capacity-loss and discharging efficiency.

Two Types are

Coulomb counting method :

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)I(t), and previously estimated SOC values. SOC(t-1) is calculated by the following equation:

SOC(t)=SOC(t−1)+I(t)QnΔtSOC(t)=SOC(t-1)+I(t)QnΔt

But there are several factors that affect the accuracy of the 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:where , and are constant values obtained from the practice experimental data.

In modified Coulomb counting method, SOC is calculated by the following equation:

Ic(t)=k2I(t)2+k1I(t)+k0Ic(t)=k2I(t)2+k1I(t)+k0

where k2k2, k1k1, and k0k0 are constant values obtained from the practice experimental data.

In the modified Coulomb counting method, SOC is calculated by the following equation

SOC(t)=SOC(t−1)+Ic(t)QnΔtSOC(t)=SOC(t-1)+Ic(t)QnΔt

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