New Boostcontrol strategy allows even easier configuration since firmware 1.2.9
Overview
- reference DC can be configured in a 2 dimension table: as a function of RPM, boosttarget
- with this "target based reference PWM duty", PID boost is easier to tune for very quick reaction and small overshoot
- if the hardware actuator is good
PID can be configured to switch to PD when boost is way too low, or to PI when boost is too high
- actually, configurable thresholds for operation ranges:
- boost off
- max-DC (to help spoolup)
- ref-DC
- ref-DC + PD
- ref-DC + PID
- ref-DC + PI
Mattias Sandgren was kind to contribute some documentation embryo - will be moved to [VT help] at "birth-time"
Begin by setting the "Boostcontrol PID integral limit" to 0 and adjust the "refDC Table vs boost target" so that you get a good starting point for enabling the PID regulated boost controller.
Apply max DC until
To shorten turbo spool time you can apply the maximum dutycycle allowed. This can only be done up to a certain limit below the boost target, set this limit here. This must be kept low enough to avoid an initial boost target overshoot that the PID regulation will not be able to stop.
PD control (far from target)
PI control (close to target)
PID overlap range
Boost P, I, D
Boost control PID integral limit
Set how large the integral is allowed to build up. This value is what is added/subtracted to the reference dutycycle in order to reach boost target. In effect setting this to 0 will disable the boost control PID regulation completely and you will just send reference dutycycle to the boost control valve.
(needs some explanation of how much x of max is, like what is normal limit, etc)
Boost PWM maximum value
Limit the maximum dutycycle the boost control valve receives.
Boost PWM minimum value
Limit the minimum dutycycle the boost control valve receives.
Copied from IRC discussions :
Overlap is PID mode, where its far enough from target to still might need the D term
PD is for not winding the integral up when too far from target
PI is close to target (its now control range)
when close to target, PI only is used, as D wouldnt make any big difference anyway
so it can be used with higher settings from far away, still not messing with close to target control
What is the buildup range and control range?
Buildup integral is frozen and control derivate is disabled. It means "too far from target, probably not physically possible to reach, don't build up a integral error" and disabling D term "close enough to target, error for P is small, so no D needed".
Overlap is PID
P is not active between max dc and buildup
Buildup = I frozen outside this range
buildup enables PD
control is PI
between buildup and maxduty there is referece only
Future ?
the buildup range might go, just enabling PD from maxduty
its easier to find the optimal P if its scaled in kpa / %
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(may2013 FPhil)This is what I get from above, I hope that is correct
| DOMAIN | zero to maxDC | maxDC to BuildUp | BuildUp to Cntrl | Cntrl to Target | Target to ? (Overlap) |
| STRATEGY | DC | ?? | PD | PI | PID |
| PARAMS | PWMmin & max | id & I limit | id & I limit | id & I limit |