Closed loop boost

[gjhome]

Hi,

I have some problems getting stable boost. I am trying the closed loop boost correction because I hade very good results with that when I had a smaller turbo.
I have attached some pictures and the log.

The problem is that the boost goes higher than the boost target, and when the pid correction kicks in it lowers the boost dc too much and the boos goes below target. It seems the pid allows quite much overboost before it kicks in, i would like it to start regulating immediately. I worked perfectly with some older firmware I had many months ago.

Do you have any suggestion how I shall modify the pid regulator values to get better response? Seems like I lack some brain cells to properly understand the pid regulation

The DC ref is set to 63 all over the table and the boost target is 250kpa. In the beginning of the log file i tried different values.

The log file is large, and in the beginning i was running open loop boost control, so disregard that parts.


Thanks!

//Gustav

[Jan32]

Hi,

it would be helpful when you upload your configuration too. I think one big problem in your settings is that the +/- feedbacks in your PID settings are at 15%, now the PID regulator can only make corrections +15% DC or -15% DC, in your case that is not enough.

You can google PID settings there is an good example how to set up PID regulator.

[gjhome]

Hi,

Thanks for the input. I attach the configuration aswell.

But as you can see from the picture in the log and the settings I have written. The boost dc table is at 63%. The requested boost is 250kpa.
The pid regulator is increasing the DC to 78% and then a maximum of 298kpa is reached without the PID is making any immediate correction. Not until
later the dc is lowered, but then too much. Why does it let the boost reach 298kpa before doing anything?

Best Regards

Gustav

[lemmy01]

Maybe a bigger kP helps.

[RHD]

Try reducing the Intigral Limit lots that might stop the overshoot, Then you may need to increase the Kp and feedback percentages to speed up the reaction.

This is what i found works well for cam control when there is a lot of oscillations and overshoot etc

[gjhome]

Thanks,

I have read up on PID control, and will try experiment with the settings. Thank you all for the help.

//Gustav

[lemmy01]

Please give use feedback if it worked and what pid setting you have changed

[gjhome]

Hi,

Its better than before.
I have tried different settings, but i really don't know how high numbers I shall use 10 or 100 or 1000? Right now I have P 12 I and D 0.
The boost overshoots slightly, its set at 250 kpa and it reach 255 and then drops to and oscillates at 200-230kpa.

I have tried different numbers on I and D like 1 5 10, but it seems to only make it worse. I consider going back to open loop again.

[RHD]

What setting do you have in the intigral limit??

[Jadzwin]

It is maximum allowable value of integral part of PID controller.
Try to set if 5 for the beginning.