Week 8 Challenge
Ultracapacitor model.
The above algorithm is implemented using the MATLAB software using Simulink blocks.
- The complete model is based on the mathematical equations which give us the accurate value of the SOC and open-circuit voltage.
- Initially from the drive cycle UC power required is if ed the UC current calculation subsystem later from the system UC output voltage and current is given to UC charge subsystem by using the equation. `Q=CV` charge is calculated and given to the SOC calculation subsystem.
- First, the algorithm of coordination between battery and ultracapacitor is done using a switch and interval test blocks and the power demanded and released value is given to the battery and ultracapacitor accordingly.
- Depending on the power demand the battery and ultracapacitor discharge accordingly and the SOC discharge is calculated using the coulomb counting method.
The subsystem of UC Current calculation
SOC Calculation of Ultracapacitor
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) + (I(t))/Q_ndeltat`
But there are several factors that affect the accuracy of the Coulomb counting method including temperature, battery history, discharge current, and cycle life.
Model output current, SOC, and Voltage.
- From the plot, we can observe voltage is decreasing because the Model is discharging and we can see that evidently by the plot of current where the current is following the drive cycle i.e when the power required is more the current increase to provide the required power the voltage above remains almost the same between 29-32 volts.