Regler Kp?

Kann mir jemand sagen, ob KP = 2 sein muss bei der Frage oder 0.5? Bitte mit einer Begründung.

Sie entwerfen einen P-Regler und dimensionieren die Regler-Verstärkung des P-Reglers zu 𝑘𝑝 = 1. Nach einiger Zeit ändert sich plötzlich die Streckenverstärkung um das Doppelte. Wie groß müssen Sie nun die Regler-Verstärkung des P-Reglers wählen, damit sich nach der Änderung der Streckenverstärkung das Führungsverhalten nicht ändert?

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AMG38
1 year ago

An increase of kp reduces the remaining control deviation. Kp does not intensify the set value, but rather the difference between setpoint and actual. A reduction of the control deviation is initially somewhat good, because it ensures that the actual size is as close as possible to the desired size.

If the route gain is now increased, the output variable is also increased.
This can lead to a reduction in the original control deviation and to a further approximation of the desired variable.

However, if one wishes to maintain the original control deviation, one must weaken here and consequently Kp must be reduced.

_______
Reproduction: revision and correction. Thank you

Lutz28213
1 year ago
Reply to  AMG38

Quote: “If the track is double-enhanced, you need a double gain on the P-member…”

And with that, the loop reinforcement would be 4 times as big as before. And this is supposed to keep the behavior of the control loop unchanged? This can even lead to instability!

AMG38
1 year ago
Reply to  Lutz28213

Guide behavior is understood to mean the behavior of the control loop to changes and a control loop has good guidance behavior if the desired variable is reached as much as possible at the output (overshooters, on-and-off control time are initially set to this point).

But I have to correct myself, but not because the increase of Kp would not reduce the deviation of the rule and bring the actual size of the desired size closer, but because it was not asked at all.

The posted question is what to do so that the leadership is not changes. That is, the output variable should remain as accurately as possible as before. That is, the previous control deviation should also remain this.

It should be simplified

W: Eingangsgröße
Y: Ausgangsgröße
E: Regelabweichung -> E = W - Y
Kp: Verstärkungsfaktor
Gr: Übertragungsfunktion des P-Reglers -> Kp
Gs: Übertragungsfunktion der Regelstrecke

The transmission function of a simplified control loop with a P controller and a control path G:

Y/W = (Gr*Gs) / ( 1+ Gr*Gs )

We want to see what we get as an initial size. To this end, we introduce a stretch reinforcement Ks. In addition, we convert the equation directly to Y.

Y = W * (Kp*Gs*Ks) / ( 1 + Kp*Gs*Ks )

If we keep the input signal constant with W = 1, Kp = 1, Gs = 1 and Ks = 1, we get

Y=0.5

It’s bad first. Because we want to achieve our desired size = 1 and are still 0.5 away. Does Kp need to be reduced so that we get closer from 0.5 to 1.

For Kp = 0.5 we get Y = 0.33
For Kp = 2.0 we get Y = 0.67

What happens if we double the line reinforcement and halve Kp from 1 to 0.5 or double to 2, while our W remains at W = 1.

For Kp = 0.5 we get Y = 0.5
For Kp = 2.0 we get Y = 0.8

By increasing the amplification, the desired variable is approached, since the control deviation is reduced.

However, since, as I said, it was not necessary to halve Kp here, so that the remaining control deviation from before is actually preserved.

Lutz28213
1 year ago

I said nothing else, didn’t I?
Note: Say everything as simple as possible, but not easier!

Lutz28213
1 year ago

H(s)=Fs*Fr/(1+Fs*Fr)

If FS is now doubled and nothing should change in function – what must happen to Fr?