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Input Format for NTGK Model (Battery Simulation)

    • enav
      Subscriber

      Hello everyone,


      I am new to ANSYS simulation and I started of duing a MSMD simulation for lithium-ion batteries. By using the NTGK model, I want to define the parameter by using the parameter estimation tool. The console informs that the format should be the following:


      -- Make sure every input file has this format --


      Crate 1.0


      time_1 voltage_1


      time_2 voltage_2


      ... ...


       


      Do you know how to include the temperature and how many data steps the simulation requires?


       


      Thanks in advance!

    • eral35
      Subscriber

      Hi enav, 


      I'm also trying to use the parameter estimation tool and having trouble. Did you resolve the issues you were experiencing?


      Regards, 


      Erik

    • seeta gunti
      Ansys Employee

      Hello Enav,


      You can use the parameter estimation tool to compute model parameters for the NTGK or ECM model, or for the One-Equation thermal abuse model. You must provide battery's testing data as a text file in a specific format for each model. When you enable this tool and select the model option, Fluent will show the required format for the input file in the console.  For each temperature you need to provide the inputs on time & voltage. For more information, you can refer the below picture. 



      Here we need to give input the temperature and curve for time vs voltage. I hope I answered your question.


      Thanks & Regards,


      Seeta Gunti

    • hfs1995
      Subscriber

      Hi Seeta,


      Thanks for the advice on that. However, I'm having some trouble finding the input file that I have created. At the moment, I'm trying to run an ECM model and I have created the input file according to the format specified but I keep running into this error message.


      Could not find file "ecm-soc01.txt". Please specify the file again!


      Is there a specific file location that I would need to place my input folder? Also would you happen to have any sample input files? Your help is much appreciated.


       


      Regards,


      Foo 


       

    • maole
      Subscriber

      Hi hfs1995,


      I am also trying to use the parameter estimation tool in ECM model and I have the same problem. If you find any sample input file I will appreciate if you send it to me.


      Regards,


      Manex

    • seeta gunti
      Ansys Employee

      I hope you guys are watched the following ANSYS how to vedios on ECM model. If not, please go through the below one which gives you more clarity on case set up.



       

    • hak19
      Subscriber

      Hi hfs1995, 


      Did you find the right location to store your .txt input files ? i am in a similar situation currently your help will be greatly appreciated.   

    • anirudhkarumuri
      Subscriber

      Try saving the data as dat file and the case as a journal, that will help you to load the case as quickly as possible.

    • anirudhkarumuri
      Subscriber

      Is there any possibility to define interval length in DOD levels in Parameter Estimation tool for NTGK model? By default one can only select between 10 to 20 DOD levels with constant INTERVAL SIZE in intermediate DOD levels.


      Furthermore,


      The console informs that the format should be the following for the input with constant Crate :


      -- Make sure every input file has this format --


      Crate 1.0


      time_1 voltage_1


      time_2 voltage_2


      ... ...


      However there is a limit(number of lines in dat file) upto which one can include the data. Can anyone clarify both the queries?


      Any leads would be appreciated. Thank you.

    • Maher Al.
      Subscriber

      Hello everyone,


      Attached screenshot, Voltage-DOD  plots for a  battery cell. On left side is the experimental data, the right side is my simulation.As you can see the difference between them. I think the problem is the model parameters I am using  ( U and Y coefficients  in NTGK Empirical Model. 


       



       


      * I would like know how to use parameter estimation tool; create and write .txt files,where to save them, how to read them, what each file contains. how are they going to be related to my voltage-DOD out files. Also, if i want to use my experimental data, what is going to change from the parameter estimation tool.


      * I Watched the video above, and it was not helpful enough.


      I appreciate you help 


       


       


       

    • Konstantine Kourbatski
      Ansys Employee

      please confirm which version of Fluent you are using

    • Konstantine Kourbatski
      Ansys Employee

      also, plot comparison on the same plot to better highlight the differences, e g. two curves per plot for each parameter

    • Tetralove
      Subscriber

      Hello kkourbat,


      Thank you for your reply,


      my previous post  was comparing the expirmental data and simulation based on 14.6 ah battery cell.


       


      Now , those plots are comparing the experimental data and my simulation based on txt files i created for 0.5,1,2,3,and 4 c discharge rates, and i am using 18.2  vision 


       




       



       


       


      thank you for your help

    • Battery
      Subscriber

      please confirm which version of Fluent you are using


       


      Hey would you mind checking my thread out, I have some troubles determining Y and U parameters of the NTGK model: 


      https://studentcommunity.ansys.com/thread/battery-ntgk-y-and-u-parameters-fitting-results/
    • Tetralove
      Subscriber


      please confirm which version of Fluent you are using


      Hey would you mind checking my thread out, I have some troubles determining Y and U parameters of the NTGK model: 


      https://studentcommunity.ansys.com/thread/battery-ntgk-y-and-u-parameters-fitting-results/

      i dont think someone will answer

      i think i figure out something , 


       



      check your charging rates

    • Tetralove
      Subscriber



      please confirm which version of Fluent you are using


      Hey would you mind checking my thread out, I have some troubles determining Y and U parameters of the NTGK model: 


      https://studentcommunity.ansys.com/thread/battery-ntgk-y-and-u-parameters-fitting-results/

      i dont think someone will answer

      i think i figure out something , 


       



      check your charging rates






    • Battery
      Subscriber




      please confirm which version of Fluent you are using


      Hey would you mind checking my thread out, I have some troubles determining Y and U parameters of the NTGK model: 


      https://studentcommunity.ansys.com/thread/battery-ntgk-y-and-u-parameters-fitting-results/

      i dont think someone will answer

      i think i figure out something , 



      check your charging rates




      µ




       


      Hey, thanks for your respsonse. I've downloaded Ansys a few weeks ago so I would say I'm using Ansys Fluent R3. I've tried different charging rates and all the results were similar. One thing I forgot to mention is that I have no experience with the meshing so I just used random numbers from some tutorial. Can this be the issue?

    • Tetralove
      Subscriber
      Hey there I dont think meshing will affect the discharging curves.
    • Battery
      Subscriber
      Hey there, I dont think meshing will affect the discharging curves.

      Idd the mesh doesn't matter alot I've tested it yesterday. I figured out that there is something wrong with my NTGK U and Y parameters but I can't figure out what I'm doing wrong. I'm not sure about my input files, here is an example:



      Crate 1.0


      0001e+00  3.400e+00 


      0068e+00  3.252e+00 


      0194e+00  3.252e+00 


      0332e+00  3.249e+00 


      0466e+00  3.247e+00 


      0597e+00  3.239e+00 


      0862e+00  3.231e+00 


      0994e+00  3.225e+00 


      1260e+00  3.217e+00 


      1392e+00  3.213e+00 


      1657e+00  3.206e+00 


      1922e+00  3.198e+00 


      2320e+00  3.188e+00 


      2585e+00  3.172e+00 


      3248e+00  3.119e+00 


      3703e+00  2.889e+00 


      3832e+00  2.576e+00 


      3878e+00  2.368e+00 


      3949e+00  2.146e+00 


      3989e+00  2.003e+00 


       



      Anyways the parameter bo is showing in a red box. This parameters must be an positive number as shown below.



       


      When I manually change the parameter b0 to let's say +1000 my thermal models are more realistic but I don't have a clue why the calculations are wrong.

    • Yevheniia Chebotarova
      Subscriber

      Hi, there. I am new one in modelling. I want to calculate U and Y coeffiecient for NTGK model, but I have no opportunaty to make an experiment. Can I use one of manufactore's graph to get coefficients? And which of them? My battery is http://liionbms.com/pdf/kokam/SLPB100216216H.pdf

      Thank you in advance.

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