Pack (Generated Block) BatteryBuilder: How can I limit my SOC from 0 to 1

I use the new battery simscape blocks for a battery simulation. Now I want to limit the SOC from 1 to 0. Actually I want to limit the single cell voltage (4.2V to 2.5V). Is this possible via the parameter table or do you have any other suggestions?

The saturator block in the Figure is actually only used to embellish my graphics and not to limit the voltage.

That only a maximum of 4.2 volts are available with a SOC of 1.

Properties: CellV = 4.2 V 24s5p with 8 Module in the pack

[Sayan]

Did you provide the cell capacity of the entire pack in the SOC Estimator block ?

[Felix]

Yes, I have indicated that

Answer 1

[Abhas]

Hi Felix,

When addressing such scenarios in which you could still charge the battery above the maximum voltage by applying a positive current to it, you should follow the below steps:

• Check the Terminal Voltage: First, look at the graph to see the terminal voltage of your battery. Remember, this might not match the open circuit voltage (OCV) or the "SOC" parameter from the block. The terminal voltage of the battery is equal to open circuit voltage plus/minus the voltage drop from its internal resistance due to current flow.
• Voltage Limitation Strategy: To keep the terminal voltage within your desired range, you can use the Simscape Battery (CC-CV) blocks. These blocks are great because they implement a constant voltage step, allowing the battery to charge fully while gradually reducing the current. This should help prevent the voltage from exceeding your set limits.
• Review Initial Settings: Review the initial conditions or targets you've set for the block. It seems both the initial "SOC" and initial voltages are being defined, which can cause some confusion or conflicts. You only need to specify one of these variables, either the "SOC" or the voltage, but not both.

You may refer to the following MathWorks documentation links to have a better understanding on Simscape battery blocks and their modeling with Simscape:

1. https://www.mathworks.com/help/simscape-battery/create-battery-pack.html
2. https://www.mathworks.com/help/simscape-battery

[Felix]

Thanks for the answer.

Which block do you mean with "Simscape Battery (Li-C) blocks"?

[Abhas]

Glad it helped!

I was referring to Simscape Battery (CC-CV) block: https://www.mathworks.com/help/simscape-battery/ref/batterycccv.html

Answer 2

[Ayush]

Hi Felix,

I understand you are facing an issue with limiting the single cell voltage in your battery simulation from 4.2V to 2.5V using Simscape blocks. Although there are multiple ways to do this such as using parameter table or power electronics(using a dc-dc converter) , here's a concise solution to address this using parameter table:

Adjust Voltage Limits:

• Open the battery block parameters.
• Set the Maximum Voltage to 4.2V and the Minimum Voltage to 2.5V.

Configure Voltage vs. SOC Table:

• In the battery block, populate the Voltage vs. SOC table:
• SOC of 1 corresponds to 4.2V.
• SOC of 0 corresponds to 2.5V.
• Ensure intermediate SOC values interpolate linearly between these voltages.

Exclude Unneeded Cells:

• Modify your battery configuration to exclude cells that are not needed. Adjust the series and parallel connections accordingly.

Optional Saturation Block:

• Use a Saturation block to enforce the voltage limits graphically, setting an upper limit of 4.2V and a lower limit of 2.5V.

For more information related to battery modelling, you can refer to the following documentation link: https://www.mathworks.com/discovery/battery-models.html

Hope this helps!

Regards

[Felix]

Thank you for your Answer.

I have already entered the maximum and minimum values. But now I can still charge my battery above the maximum voltage by applying a positive current to it. This is not intercepted by the maximum voltage.