Burkert 8625-2, Руководство по эксплуатации

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28 - 8625-2 Standard
english
1
T
i
characteristic and step response of the P fraction of a PI controller
Characteristic Step response
Control range
∆
x
c
Correcting range
∆
y
Floating time T
i
I fraction:
Function: y =
∫ ∫ ∫ ∫ ∫
x
d
dt
T
i
is the integration or floating time. It is the time that expires until the controller
output has run through the entire correcting range.
Characteristic:
A purely I controller completely eliminates the effects of disturbances. It thus has a
favourable static behaviour. Because of its finite correcting speed, it works more
slowly than a P controller and tends to oscillation. It is hence dynamically relatively
unfavourable.
Superimposing:
With a digital controller with sampling time T
A
and noting that T
i
= K
p
/T
N,
one can
write:
y = K
p
(x
d
+ T
A
/T
N
∑ ∑
∑ ∑ ∑
x
d
)
y : controller output
K
p
: amplification factor
x
d
: deviation (x
d
= w - x)
T
A
: sampling time
T
N
: reset time
y
max
x
d
y
min
x
d
x