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Electronic wastegate actuator

PostPosted:Wed Aug 08, 2018 2:12 pm
by LewisR
Hi all,

This is my first post, let me know if I have missed something... I did check for a similar topic but didn’t find anything.

I am building an engine which includes a turbo charger which has its wastegate controlled by an electronic actuator which also provides positional feedback.

Is there scope to add an additional boost control feature to allow for such devices?

Depending on the interest, I have some specs of the actuator and do plan on testing offline on an Arduino to confirm how it is controlled.

:D

Re: Electronic wastegate actuator

PostPosted:Wed Aug 08, 2018 6:56 pm
by PSIG
Welcome! :) It might, depending on how the actuator is controlled, and what feedback(s) you wish to use in boost control. Currently, Boost Control uses TPS position versus engine RPM in order to target a specific MAP target (3D table) of varying PWM duty cycle, either in open-loop or closed-loop with tuneable PID. Being Speeduino is open-source, you can change the parameters and functions how you wish, or request changes if you know what you need.

David

Re: Electronic wastegate actuator

PostPosted:Wed Aug 08, 2018 8:37 pm
by dazq
I too would be very interested to see the data on controling the wastegate actuator ,as a few turbos I have seen recently have had electronic types.
What engine is the turbo from originally? What is it going on now?

Re: Electronic wastegate actuator

PostPosted:Thu Aug 09, 2018 1:57 pm
by LewisR
Thanks for the welcome and the inputs guys.
Can’t name the vehicle but it is from an exotic 4.0 twin turbo V8. :lol: :twisted:
It is going on an mx5 engine rebuilt from the bottom up.

I think I can work with TPS and RPM as inputs. This can map against target pressure... I think without a lot of dyno time I wouldn’t be able to get enough data to map against WG position. However having the positional feedback will give some added control and safety. I.e you could ensure it is full open or closed at certain times.
I would like to get an understanding of boost vs WG position as this would allow fine control for example if I know that closing the WG by 5% would yield an increase of 3psi that would be useful.

My next steps will be to understand what the actuator needs to move which I will be testing soon.

Re: Electronic wastegate actuator

PostPosted:Thu Aug 09, 2018 4:25 pm
by PSIG
Well, details on the control of your specific turbo will be needed of course; although most variable-geometry turbos (DC electric and regulated oil pressure types) can be controlled by Speeduino PWM as-is. Most. ;) Indeed, open-loop is a virtual requirement in order to establish the operating parameters and vane position relative to resulting MAP as basic setup info, but keep in-mind it is dynamic for any system, including VNT/VGT. However, vane position is not required for control, as the system in closed-loop will simply add or subtract duty cycle in order to reach target. Position feedback is nice to have in order to detect and report sticking or operating failure, but a user-set ignition boost-cut feature is in Speedy to help avoid engine damage from over-boosting. Again, you can configure or re-task the system however you like. 8-)

David

Re: Electronic wastegate actuator

PostPosted:Thu Aug 09, 2018 6:13 pm
by lsdlsd88
at the end of the day from what I know the positional feedback is used only to detect faults, nothing to do with the boost control algorithm.

Re: Electronic wastegate actuator

PostPosted:Thu Aug 09, 2018 10:54 pm
by LewisR
This isn’t a variable vane turbo, the actuator is controlling the wastegate. However you maybe right, it may accept the current pwm to drive it. That, I shall find out when I test it, hopefully will have a set up tomorrow.

As for the positional feedback, speaking to the controls guys that work with this turbo, it plays a considerable part in there control algorithm as well as learn cycles to determine position after heat expansion. However this is probably not necessary for my one off application.

Re: Electronic wastegate actuator

PostPosted:Sat Aug 11, 2018 11:48 pm
by noisymime
I've seen and played with a Bosch electronic wastegate setup and it's driven exactly the same way as you would a traditional wastegate actuator. The system fails open and takes a PWM signal that progressively closes the wastegate to increase boost. The only difference is that you don't have a spring to give you a default level of boost.

I can't say that's how every one of these works, but I'd be surprised if there are big differences