[Battery]

Hello,

For my thesis I'm designing a batterypack for an application. Currently I'm trying to determine the U and Y coefficients for the NTGK battery model. Because I'm not able to do any experiments yet I used a graph delivered by the battery supplier (Voltage in functon of time in minutes). You can see the graph below. I extracted the values from the graph and wrote them in three .txt files (1C;2C and 3C). Completely below the text files are shown.



With the parameter estimation tool I've readed the .txt files into Ansys. The tool calculated the Y and U parameters as shown below. I also added the model options (50Ah 3,2V pouch cell). As you can see the parameter bo isn't correct because it's shown in a red box. This parameter should be a positive number.





The experimental and fitted results are shown below. As you can see these results doesn't match the first graph at all and I can't figure it out what I'm doing wrong.





Text file 1C rate (time in seconds | voltage in V):

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



Text file 2C rate:

Crate 2.0

0001e+00 3.400e+00

0060e+00 3.187e+00

0200e+00 3.178e+00

0333e+00 3.172e+00

0465e+00 3.165e+00

0598e+00 3.156e+00

0730e+00 3.151e+00

0863e+00 3.141e+00

0995e+00 3.131e+00

1261e+00 3.108e+00

1515e+00 3.058e+00

1656e+00 2.976e+00

1744e+00 2.838e+00

1776e+00 2.750e+00

1802e+00 2.599e+00

1825e+00 2.504e+00

1850e+00 2.383e+00

1892e+00 2.195e+00

1901e+00 2.101e+00

1913e+00 2.012e+00




Text file 3C rate:

Crate 3.0

0001e+00 3.400e+00

0001e+00 3.134e+00

0134e+00 3.118e+00

0267e+00 3.109e+00

0400e+00 3.098e+00

0532e+00 3.090e+00

0665e+00 3.073e+00

0798e+00 3.055e+00

0919e+00 3.027e+00

0997e+00 2.990e+00

1041e+00 2.955e+00

1075e+00 2.912e+00

1087e+00 2.869e+00

1113e+00 2.823e+00

1155e+00 2.623e+00

1201e+00 2.472e+00

1198e+00 2.388e+00

1226e+00 2.219e+00

1226e+00 2.180e+00

1250e+00 2.009e+00

[Battery]

This is how the console in Ansys looks like:

[Battery]

Bump

[AlexanderZ]

you can fit parameters yourself, google paper regarding NTGK method
for example:
K. H. Kwon et al. “A Two-dimensional Modeling of a Lithium-polymer battery”. Journal of Power Sources.
163. 151-157. 2006.

[thialves98]

Hi, did you end up getting the right parameters of U and Y coefficients? If so, can you please explain me how you did it? Thanks in advance

[blacksatellite]

did you solve?