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Step function for battery module

Posted Feb 25, 2016, 4:01 p.m. EST Parameters, Variables, & Functions Version 5.1 10 Replies

Anna Nordh
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Hello.

I would like to create a discharge and charge cycle by using a step function. It is for Li-ion battery.

I've managed to create only one pulse by define equation for discharge and charge:

disch_on step1((t_disch_stop-t)[1/s])
charge_on step1((t-t_disch_stop-t_ocp)[1/s])*step1((t_charge_stop+t_disch_stop+t_ocp-t)[1/s])

These equations create only one pulse but I would like to create several pulses. Could you please help me to go on with second step?

Thank you very much!
10 Replies Last Post Feb 10, 2017, 5:31 p.m. EST
Lasse Murtomäki
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Posted: 9 years ago Feb 26, 2016, 1:55 a.m. EST
Hi

I have kept on replying the pulse question with an equation I developed when I needed a long sequence of pulses. Please, see the attachment.

BR
Lasse
Hi I have kept on replying the pulse question with an equation I developed when I needed a long sequence of pulses. Please, see the attachment. BR Lasse

Attachments:

Anna Nordh
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Posted: 9 years ago Feb 26, 2016, 3:00 a.m. EST
Thank you for your answer, Lasse.

Which "function form" is your equation applicable for? Could it be wave function with rectangular steps?
Thank you for your answer, Lasse. Which "function form" is your equation applicable for? Could it be wave function with rectangular steps?
Lasse Murtomäki
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Posted: 9 years ago Feb 26, 2016, 4:23 a.m. EST
My function produces a sequence of square wave pulses with an arbitrary pulse width and separation (i.e. duty cycle) and frequency. Multiplying it with something else, several types of periodical functions can be created; my functions simply goes on and off (1 or 0).

BR
Lasse
My function produces a sequence of square wave pulses with an arbitrary pulse width and separation (i.e. duty cycle) and frequency. Multiplying it with something else, several types of periodical functions can be created; my functions simply goes on and off (1 or 0). BR Lasse
Jeff Hiller COMSOL Employee

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Posted: 9 years ago Feb 26, 2016, 8:10 a.m. EST
Hello Anna and Lasse,
I would like to point out a simpler way of doing this. It consists in using either:
a/ a Function of the "Waveform" type. Use this approach if the periodic signal is sinusoidal, triangular, square, or a sawtooth. See the attached file.
or
b/ a Function of the "Analytic" type with the "Periodic Extension" option checked on. Use this for other periodic signals. See the attached file, where the Analytic 1 function periodicizes the Interpolation 1 function.
Best,
Jeff
Hello Anna and Lasse, I would like to point out a simpler way of doing this. It consists in using either: a/ a Function of the "Waveform" type. Use this approach if the periodic signal is sinusoidal, triangular, square, or a sawtooth. See the attached file. or b/ a Function of the "Analytic" type with the "Periodic Extension" option checked on. Use this for other periodic signals. See the attached file, where the Analytic 1 function periodicizes the Interpolation 1 function. Best, Jeff

Attachments:

Lasse Murtomäki
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Posted: 9 years ago Feb 26, 2016, 8:14 a.m. EST
Thanks Jeff!
That also solves the question of the duty cycle.

BR
Lasse
Thanks Jeff! That also solves the question of the duty cycle. BR Lasse
Anna Nordh
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Posted: 9 years ago Feb 27, 2016, 6:25 a.m. EST
Jeff and Lasse, thank you so much!
Jeff and Lasse, thank you so much!
Anna Nordh
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Posted: 9 years ago Feb 28, 2016, 3:52 a.m. EST
Jeff, could you possibly send file applicable for 5.1 version? I tried to open your file with my Comsol without any success.
Jeff, could you possibly send file applicable for 5.1 version? I tried to open your file with my Comsol without any success.
Farnaz Tajdari
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Posted: 8 years ago May 31, 2016, 12:00 p.m. EDT
Hi Jeff,

Could you please also send the attached file for COMSOL 5.1?
I also cannot open the file.

Kind regards,
Farnaz
Hi Jeff, Could you please also send the attached file for COMSOL 5.1? I also cannot open the file. Kind regards, Farnaz
Certified Consultant
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Posted: 8 years ago Aug 17, 2016, 11:31 p.m. EDT
Hi Jeff,

I would also be very happy to get your file for Comsol Version 5.1

Cheers, Vanessa
Hi Jeff, I would also be very happy to get your file for Comsol Version 5.1 Cheers, Vanessa
Walter Frei COMSOL Employee

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Posted: 8 years ago Feb 10, 2017, 5:31 p.m. EST
Hello All,
When modeling a pulsed load, also consider if the load will turn on or off instantaneously. If you do expect abrupt switching between states, use the Events interface.
For a discussion about why, please see:
www.comsol.com/blogs/modeling-a-periodic-heat-load/
Hello All, When modeling a pulsed load, also consider if the load will turn on or off instantaneously. If you do expect abrupt switching between states, use the Events interface. For a discussion about why, please see: https://www.comsol.com/blogs/modeling-a-periodic-heat-load/

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