Parameters / Conditions For 2nd Closed Loop Operation

.21.00.00 Parameters / Conditions For 2nd Closed Loop Operation

Conditions for closed loop operation of the second control loop
As already mentioned under "General" the 2nd control loop optimizes the adjustments of the first control loop over a longer time to achieve the maximum conversion of the catalyst in a very small window of air/fuel ratio close to Lambda = 1. The second control loop uses a binary Oxygen sensor which is operated at a target value of sensor output voltage. Deviations from the target voltage are corrected by adjusting the air/fuel ratio until the target voltage is achieved again. The controller of the 2nd control loop is a combination of proportional and integral (PI-) controller. The proportional and the integral portion of the controller have individual enable criteria.

Parameters evaluated to begin closed loop (second control loop)

Enable criteria for P-portion of the controller
The proportional-portion of the controller corrects short term deviations and achieves the target sensor output voltage.







Enable criteria for adaptive I-portion of the controller (additionally)
The integral-portion of the controller corrects permanent deviations / shifts over a longer time by adjusting the adaptation.







Typical Values (second control loop)
Given a normal cold started FTP (around 20 degrees C) most of the concepts reaches the closed loop condition for the second control loop within 60s to 100s.