Question about simscape battery library parameters(table-based) supplied by battery company.

There is a Battery Parameter provided from battery Supplier in Battery(Table-Based) block.

I can't upload the image, so i will write the parameter for example.

I wonder that Panasonic NCR18650PF battery parameter.

I generally know, battery parameters( V0, R0, R1, tau1) are sorted by SOC.

For example, Panasonic NCR18650PF data has 101 SOC section. [101 x 1]

[0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1 0.11 0.12 0.13 0.14 0.15 0.16 0.17 0.18 0.19 0.2 0.21 0.22 0.23 0.24 0.25 0.26 0.27 0.28 0.29 0.3 0.31 0.32 0.33 0.34 0.35 0.36 0.37 0.38 0.39 0.4 0.41 0.42 0.43 0.44 0.45 0.46 0.47 0.48 0.49 0.5 0.51 0.52 0.53 0.54 0.55 0.56 0.57 0.58 0.59 0.6 0.61 0.62 0.63 0.64 0.65 0.66 0.67 0.68 0.69 0.7 0.71 0.72 0.73 0.74 0.75 0.76 0.77 0.78 0.79 0.8 0.81 0.82 0.83 0.84 0.85 0.86 0.87 0.88 0.89 0.9 0.91 0.92 0.93 0.94 0.95 0.96 0.97 0.98 0.99 1]

And then , I think V0, R0, R1 and tau1 should have same range. [101 x 1]

V0, R0 have same size to SOC

V0 : [2.80555 2.85959 2.91363 3.00304 3.0606 3.09933 3.12978 3.18381 3.23096 3.26469 3.2911 3.31202 3.33368 3.35023 3.3665 3.38187 3.39652 3.40935 3.42296 3.43602 3.4475 3.45894 3.46943 3.47583 3.48131 3.48929 3.49863 3.50723 3.51419 3.52064 3.52703 3.53288 3.5383 3.54248 3.54635 3.55067 3.55538 3.56162 3.56772 3.57355 3.57907 3.58466 3.59099 3.59795 3.60491 3.61176 3.61856 3.62438 3.62996 3.63625 3.64309 3.64978 3.65633 3.66344 3.67149 3.67995 3.68883 3.69977 3.7106 3.72128 3.72977 3.73862 3.74839 3.75854 3.76808 3.77731 3.78691 3.79724 3.80748 3.817 3.82465 3.83227 3.8402 3.84937 3.85948 3.87001 3.88001 3.88909 3.89708 3.90554 3.91623 3.9276 3.9408 3.95458 3.96671 3.97597 3.98588 3.99921 4.01279 4.02654 4.03959 4.05214 4.06294 4.07257 4.08033 4.08863 4.09953 4.11328 4.13091 4.15201 4.17387]

R0 : [0.17403 0.14702 0.12022 0.10415 0.08835 0.07462 0.06392 0.06243 0.06276 0.06157 0.06015 0.0587 0.05791 0.05742 0.05726 0.05695 0.05669 0.0563 0.05643 0.05637 0.05613 0.05627 0.0562 0.0555 0.05463 0.05424 0.05396 0.05353 0.05325 0.053 0.05273 0.05239 0.05185 0.05104 0.05016 0.0496 0.04917 0.049 0.04873 0.04841 0.04805 0.04775 0.04765 0.04766 0.04767 0.04767 0.04767 0.04746 0.04718 0.04683 0.04661 0.04638 0.04611 0.04546 0.04498 0.0446 0.04436 0.0447 0.0452 0.04568 0.04568 0.04565 0.04553 0.04551 0.04545 0.04533 0.04532 0.0455 0.04565 0.04568 0.04547 0.04525 0.04509 0.04486 0.04471 0.04473 0.04488 0.04509 0.04508 0.04519 0.04567 0.0459 0.04653 0.04736 0.04774 0.04743 0.04723 0.04771 0.04823 0.04878 0.04933 0.04973 0.0497 0.04945 0.0488 0.04782 0.04663 0.04586 0.04557 0.04146 0.03511]

But R1, tau1 have [7 x 1].

R1 : [0.0029 0.0024 0.0026 0.0016 0.0023 0.0018 0.0017]

tau1 : [36 45 105 29 77 33 39]

I don't know what mean it is.

Please help

Thank you.

Answer 1

[Shivam Gothi]

Hello @인규,

As I understand it, you are attempting to simulate a battery using the Simulink library block "battery (table based)," with specifications provided by the manufacturer. However, the sizes of the vectors "tau1" and "R1" do not appear to match the sizes of the vectors "SOC" and "Vo."

To address this, let's consider a brief description of the relevant fields:

• Vector of state-of-charge values, SOC: This is a vector of state-of-charge breakpoints that define the points at which you specify lookup data. This vector must be strictly ascending. For the battery you specified, it has a size of (1, 101).
• Vector of temperatures, T: This is a vector of temperature breakpoints that define the points at which you specify lookup data. In your case, it has a size of (1, 4).
• Open-circuit voltage, V0(SOC): If you are not modeling temperature dependency, it has the same size as the "SOC" vector. Therefore, in your case, it has a size of (1, 101).
• Open-circuit voltage, V0(SOC, T): If you are also modeling temperature dependencies, it will have a size of (length_temperature_vector, length_SOC_vector). Therefore, for the battery you specified, it is (101, 4).

Now, regarding the parameters "tau1" and "R1," these parameters are used to model the charge dynamics of the battery.

• "tau1" vector: Contains the lookup data for the first parallel RC time constant at the specified SOC.
• "R1" vector: Contains the lookup data for the first parallel RC resistance at the specified SOC.

Both of these should have sizes of (1, 101) for the simulation to run properly. However, in the battery, they have a size of (1, 7) because the charge dynamics are not modeled, rendering "R1" and "tau1" insignificant. They are simply set to their default values:

• R1: [0.0029, 0.0024, 0.0026, 0.0016, 0.0023, 0.0018, 0.0017]
• tau1: [36, 45, 105, 29, 77, 33, 39]

If you want to also model the charge dynamics, set the “Charge dynamics” property to One time-constant dynamics as shown in the below figure.

Now, you can manually enter “tau1” vector and “R1” vector. But remember that the sizes of both the vectors should be:

• (1,101) if you are not modelling temperature dependency
• (101,4) if you are modelling temperature dependency.

The information regarding the modelling of “charge dynamics” is not taken from the data sheet of the manufacturer. Therefore, you have to manually enter it by referring to the technical manual, if they are provided.

Conclusion:

The sizes of “R1” and “tau1” vectors must match the size of “SOC” and “Vo” vectors, only if they are modelled.

I hope it answers the question !

[인규]

Thanks for kind reply shivam.

To summarize what you're saying, you mean I have to manually input R1 and tau1 based on the battery manufacturer's specifications, right?

You're saying that this information is not included in the Simscape Battery library?

[Shivam Gothi]

Hello @인규,

Yes. You understood it perfectly.

for panasonic : NCR18650pf, the charge dynamics are not modelled. Therefore, "R1" and "tau1" are of no significance. But if you want to model the charge dynamics, you will have to enter it manually or load from the workspace.

Kindly refer the below link for more information:

https://www.mathworks.com/help/releases/R2024b/simscape-battery/ref/batterytablebased.html#mw_be661e7b-a0ea-457a-b51f-21e711a9141d