I'm currently modelling an engine crankshaft in LMS AMESim and am using the submodel TRCS003A. Which calculates the dynamics of the crankshaft with regard to a pressure on the piston.
To regulate the rpm of the crank shaft, I am using an PID controller to regulate the output revs to a predefined reference rpm. However, when I reach the desired rpm-value, the PID controller outputs a zero value. (which is preferred).
What I do wonder is: if the model takes the pressure of the compression stroke into account without defining it separately.
Or do I need to specify my combustion pressure and the pressure from the compression stroke.
I hope you can help me!
With kind regards,
Solved! Go to Solution.
Thanks for your reply. Based on your comment, I believe my assumption was correct that there is no internal way in the model of creating a pressure (it solely relies on a [null] input value).
I do have a follow-up question on this part. It's true I modelled the in-cylinder pressure tabel in to the 1D-table submodels.
My original thought was to create a table recreating the pressure from combustion and let this be regulated by the PI-controller. After the multiplication with the PI-controller and 1D-table, I wanted to add another 1D table to model the in-cylinder pressure caused by the compression stroke. Then add this to the value regulated by the controller, thus recreating a regulation of the injected fuel.
But if I understand correctly, the 1D-table containing the compression pressure, will cause a force on the piston as well.
Does this (fictuous) accelaration have to be regulated via a second controller or modelled friction?
Thanks for the tips!
In the Amesim demo models, the in-cylinder pressure table is defined from 0 to 720 degrees, and should therefore include the intake, compression, combusion and exhaust stroke together. You want to seperate this out and create one table for the compression (~180 to ~360 degrees) and one for the combustion (~360 to ~540 degrees) and then only apply a controlled gain to the cumbustion part. Take a look at the attached image which does what I think you want to do.
The compression pressure will lead to a nett negative torque (slowing down the crankshaft) so the controller will then have a nonzero mean value (to create a nett positive torque from combustion) to counteract the compression.