How to achieve parameter estimation for time stepping

[Santiagopeacely]

Dear developer:
Hello, during the simulation, there are some parameters that are not constant, but change as the reaction proceeds, or, rather, change over time, how does this work in parameter identification? Looking forward to your reply, thank you！

[BradyPlanden]

Hi @Santiagopeacely,

Can you be a bit more specific on which parameters you are looking to identify? For example, you can identify parameters as a function of state-of-charge, temperature, or other operation conditions by forming a piece-wise linear interpolation. At the moment, we don't yet have functionality to decoupling parameters that change over cycle-life; however, depending on how you represent the changing dynamics, you could formulate a relationship that has scalar parameters but is predicting the underlying mechanism. A MWE of your proposed identification workflow would be great for us to continue this discussion.

[md-aseem]

Hi @BradyPlanden I am looking for estimating parameters as a function of SOC. Do we have any example of this implementation somewhere?

I tried looking at the HPPC multipulse notebook, but it seems like it trains for one set of parameters(not as a function of SOC) for all the pulses.

I also attempted to use the parameter set at pybamm/input/parameters/ecm/example_set.py in which parameters are defined as function of SOC, temperature, but when I tried to optimize this through the HPPC multipulse notebook way, it gives below error:

ValueError: Optimised parameters do not produce a finite cost value

Thanks!!!!

[Santiagopeacely]

Dear developers @BradyPlanden, good day! Suppose I want to identify the functional parameter of electrolyte diffusivity. This parameter changes with the state within a single cycle. However, if I conduct the identification using the data of the entire cycle, the result will be a constant parameter. To identify such a parameter, do I need to perform the identification at each sampling point rather than using the full charge-discharge voltage data of the entire cycle? Could you please help me with this? Thank you very much!