Hello people,
I am developing an Equivalent ckt. model(ECM) of an Li-ion battery using Zview software. This ECM will be implemented in automotive BMS, with sampling rate of (5-10)Hz.
I am a bit doubtful about whether to include an inductor in the ECM to represent the positive imaginary part of impedance (which is the result of inductance).
Some research papers have included it in ECM while some have not.
I believe that it depends on the sampling rate and load cycle frequency application where the developed ECM would be implemented.
I have attached below one of the nyquist plot I am using in this task. Here the magnitude of inductance is so large.
Your suggestions are so valuable.
High frequency inductance comes from the setup or wiring. You can reduce the high frequency range and exclude the inductance by using better test setup. what is your frequency range?
Dear Raam,
Thanks a lot for your answer. The EIS measurement frequency range is (10 kHz - 0.1 mHz). Unfortunately I have to stick to this frequency range as per the test procedure.
I could understand the sources of inductance from test setup, but I am a bit puzzled on whether such an inductance behavior will be observed in an automotive battery pack.
Some researchers say that there would be some considerable inductance effect observed in a battery pack during operation which cannot be neglected while developing an ECM and some say this inductance effect shall be neglected while developing an ECM.
Dear Barani,
Give more rest period at OCV state before making the impedance. Sometimes inductive loop arise when non-uniform lithiation happens in a porous electrode such that the transfer of charges are involved between highly lithiated to poorly lithiated part of same electrode separated by SEI (Concentration cell effect). After bias potential, give adequate rest and measure the impedance in OCV state, that might help. Mostly it can happen due to geometry, try to maintain all the parameter constant.
Dear Raam,
Thank you for your suggestion. I will try to do so.
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