Luftmengenmesser AAT - Gedankenspiel | Posts 16+

Quote:

At approximately 0.6 bar, the boost pressure in our turbochargers is completely unregulated (the wastegate only opens at 0.6 bar)

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JAIEN, in my opinion, that's not the whole truth. If we only consider the internal control loop (with the N75 disconnected), the WG must start to open BEFORE 0.6 bar. An indication of this is that the 0.6 bar is reached without any overshoot (only at 3000 RPM at full load), and that without the N75, the increase in LD (Lambda) is already less pronounced BEFORE 0.6 bar than with the N75. (I logged that once, but I can't find the file anymore ).

At full load and rated speed, it's really quite clear.

Furthermore, the purely mechanical WG (wastegate) regulation acts as a simple proportional (P) controller. This type of controller always has a persistent control error because without a control error, no control output is generated, resulting in the wastegate being closed. This means that if the wastegate were to open only at 0.6 bar, some kind of pressure sensor would need to be set above 0.6 bar.