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Few problems in modeling with Simscape Driveline

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Ayush Sharma
Ayush Sharma on 23 May 2019
Answered: Steve Miller on 6 Aug 2020
Hello all,
I've been watching all the MATLAB tutorials on physical modeling for the past few days and have been simultaneously trying modeling a powertrain system for a BAJA vehicle. Even after reading the documentation and watching the videos again and again, there are few problems that I haven't been able to solve. Please help me out.
The issues I've faced are as follows :
(1) Whenever I use a variable transmission, if I measure the engine RPM it's oscillating in nature. This could be because of those "damping" and "stiffness" variables in that unit, but I haven't been able to find some explanation for these variables as in what they represent.
(2) I've input my engine torque vector as [2000 2200 2400 2600 2800 3000 3200 3400 3600]. I gave an initial RPM of 2100. The solver warns me that after 7.83 s the engine rotational speed exceeds the maximum speed, trying to fix which I set the redline as 3600 RPM. But even then I am facing the same issue.
(3) When I use an RPM sensor connected in series/parallel to the engine I get a starting from 200 RPM, but shouldn't it be 2100 RPM ?
Please help me out.
I have attached the model below.

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Answers (1)

Steve Miller
Steve Miller on 6 Aug 2020
You nearly had it all working. :) I have attached an adjusted model.
Your Redline Speed parameter was at the upper limit of your Torque/Speed curve, so by the time the redline controller took action, it was already too late. In the attached model I set the Redline Speed to a value below 3600.
Your engine was starting at 2100 RPM. Your scope said 220 because you hadn't specified that you wanted the units to be in RPM. Setting the units in the PS-Simulink converter to "rpm" reveals the engine is starting at the desired speed.

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