SOC Estimate Calculation of Calculation

I'm Rohan Doijode, working as a Design Engineer.

I'm trying to simulate an electric vehicle in MATLAB using Simulink, Simscape Driveline, Simscape Electrical and Powertrain blockset.

Currently a fresher to this software, I'm trying to refer this figure attached above for simulating and finding out State of Charge at the end of the cycle.

Can anyone guide me how to approach and build the system (marked red in figure) ?

I'm attaching the file to the post

Thanks in advance !

Answer 1

[Mike Sasena]

Hi Rohan,

Probably the simplest method you could try would be to try "Coulomb counting". You use an integrator block on the incoming current signal to either increase or decrease the net charge in that subsystem. The SOC is then simply the current charge divided by the total max charge. It will be imperfect and drift over time, but it's a good first order approximation that you can implement with just a few blocks.

[MAHENDRAN A]

Hello Sir,

I'm Mahendran, thanks for your explanatiion in coulomb counting. Can you say the same for kalman filter too. Like how to make a model for SOC estimation using kalman filter method.

[Mike Sasena]

Hi Mahendran,

Yes, that's definitely a more rigorous (and more applicable to the real world) method. There's an example in our documentation to show you how this can be done:

https://www.mathworks.com/help/simscape-battery/ref/socestimatorkalmanfilter.html

[MAHENDRAN A]

Thank you for the answer sir,

I've doubts on developing SOC estimation using coulomb counting method. Ive developed a basic logic model which im attaching for you're referrence. Can you explain me in detail about how to model an SOC estimation profile using coulomb counting for charging and discharging profile.

Answer 2

[Mike Sasena]

Hi Manhendran,

There are several existing examples in both Powertrain Blockset and Simscape that may help you understand how to do SOC estimation, e.g.:

• EV Reference Application: Look in the "EvReferenceApplication/Controllers/Powertrain Control Module (PCM)/Battery Management System (BMS) (BMS_Software)" subsystem
• Battery State-of-Charge Estimation: Show how to use the SOC Estimator (Kalman Filter) block

There are also detailed videos like this one on SOC Estimation.

Hope that helps,

Mike