VEMS new boost control guide.

[james]

I understand I will alter the piping to my solenoid,

as I have a 1 bar spring in my waste gate which way of the two you recommended for finding the duty cycle% would you use? Would they both still work As obviously below 1bar the duty cycle will have no effect on boost?

Thanks for you advice

[james]

anyone tried this yet? im having trouble finding the correct duty cycles what gear are you meant to do pulls in? I have been doing them in 2nd the find it overshooting the target massively in 3rd gear :'(

[fphil]

I read and reread, the documentation and Gunni's guide and I feel stupid not to underdand why the Boost PE value is so crazy and negative.

I shall be thankful if someone can explain that to me

[VEMS]

Hello Philippe,

Simple answer: Boost PE is calculated by VemsTune and VT calc model is not up to date for the new boost control. Reported boost integral should be good this is a real-time variable.

Best regards, Dave

[fphil]

Does someone knows when the Boost Integral value reset to zero?
In my case never once the boost integral action is used for some values. This is even when returning to idle.
So when entering the PI domain for a new time the I value is not zero but has  some value which was reached in a former action. Is it planned so?

btw speaking about possible or not planned property , I noticed that when RPM < IACTargetRPM  the IdleIgnitionControl is active even when TPS is not zero.

[gunni]

I don´t think there is any reset for the Boost Intergral as soon as your I is enabled it will move quickly. I would do some tests and if you find you are getting inconsistent results advice VEMS to implement a reset system. If you are left with big I values you need to revisit your DC_ref table.

So ignition is being raised to counter rpm dropping below the Idle target? Unless its clear that is should do so then its effectively a bug and you should report it via the reporting feature in Vemstune.

Any un-documented features should be reported so that they can be documented if planned or removed if unplanned.

[fphil]

I think I have reported.
As for the Boost, during many years of practice in system control, I was mostly used with an integral action being reinitialized whenever the system state enters some specific domain which have been set around the target. On another hand it means nothing to tune the  DC_ref  boost table, say @ 70kPa, when no boost is of use. So to be sure not to be bothered with the table one put the entries  = 100% for such map values. Hence the I action is quite large when the actual map enters the boost I domain.
But this is not much important and besides I may have missed something...

[gunni]

This is why you can control at what point the I becomes active again

[fphil]

indeed, but that value of I means nothing, better to enter with a zeroed value

[VEMS]

Hello Phil,

Is your boost control working properly using the new algorithm in open loop with PID = 0 ? With boostcontrol it is imperative to tune the reference table properly for all boost targets first.

Best regards, Dave

[fphil]

No it is not. Doing so, as Gunni said, I agree the I integral should be zero on a static mode. However it occurs that you have to leave the boost target domain before reaching the target and before the integral term has decreased to zero (assuming that refDc table is ideal). Hence past I values may accumulate.
I see no problem to reset the integral term when entering the target domain. The advantage is that this releases the constraint to search for a good open loop control every where before setting the closed loop. A feedforward term might be seen as an help to the control action for  getting about the target, the last step to the target being done by the integral action.