Simscape 1RC battery model without having experimental data

Hi all, I want to develop a Simsape battery model with 1RC component, but I don't have OCV-SOC experimental curve to compare with the simulation results. Even if I start with an initial guess for OCV, Ro, R1 and C1, I can't use the parameter estimation tool for comparison because I don't have the curve. Is there any way to proceed with the modelling or is it impossible to start modelling because there is no experimental data? Note: I have all the cell information from the supplier, only the curves are missing.

Answer 1

[Xiangchun]

Hi Nitish,

It is generally recommended to use experimental data to parameterize cell blocks such as Battery (Table-Based) or Battery Equivalent Circuit provided by Simscape Battery.

If such experimental data are not available, it is also possible to extract parameters like open circuit voltage (OCV) and instantaneous resistance (R0) from a detailed battery specification sheet provided by the battery supplier if the spec sheet contains discharge curves under different C rates.

It is generally acceptable to use a low rate (C/10 or lower) discharge curve as an approximation of the OCV. The discharge curves (voltage vs capacity plot) under different C rates on a typical detailed battery specification sheet can be used to extract R0. Here is an example showing how this can be done: Generate Parameter Data for Datasheet Battery Block - MATLAB & Simulink (mathworks.com).

It is generally not possible to estimate R1, C1, or Tau1 from a battery specification sheet without conducting pulsed current based tests of batteries.

With OCV and R0 parameterized, the model would be able to capture most of the battery behavior, especially the instantaneous voltage loss under load or boost during charge. But it does not model additional charge dynamics, which has to be described by R1, C1, or Tau1.

Best wishes,

Xiangchun