Siemens SIPART DR22 Manual page 95

Manual 1 Technical Description
1.5 Functional description of the structure switches
1.5.5 Control algorithm, parameter control, adaptation
Manipulated variable limiting yA, yE (yAII, yEII at S1=12)
The manipulated variable limiting with the parameters YA and YE is active in automatic opera-
tion in any case. The limits of these parameters are at --10 and +110 %. However, it should be
taken into account that the controllers neither output negative actuating currents nor detect any
negative position feedback signals.
If the manipulated variable y reaches one of the limits YA or YE in automatic mode, further in-
a
tegration is aborted to avoid integral saturation. This ensures that the manipulated variable can
be changed immediately after reversing the polarity.
In manual-, follow-up- (DDC) or safety operation the manipulated variable y can be driven out of
the limiting range (only at S245=0 or S246=0). When switching to automatic mode the last
manipulated variable is transfered bumplessly, then only changes in the manipulated variable in
direction of the range YA to YE are executed.
In controller I the manipulated variable limiting is only possible in K-controllers and
three-position step controllers with external position feedback (S2=0 and S2=3).
Adaptive filter
The control difference xd is fed through an adaptive filter. By adjusting tFI or tFII (onPA) from
oFF to 1 s the filter is switched on. By further increases to tF* the filter can be adapted to a low-
frequency disturbance frequency (seconds to hours time constant). Within a band in which
changes repeatedly take place, changes are seen as disturbances by the filter and are filtered
with the preset time constant tF*; Changes in a direction leading out of the band are passed
unfiltered to the Pi(D) algorithm to enable fast control. If the disturbance level changes in time,
the filter is automatically adapted to the new level.
E
t
A
t
Figure 1-52 Effect of the adaptive non-linear filter
The factory setting of tFI and tFII is 1 s. In controllers with D-part it should be set as great as
possible because of the input noise amplified by vv ·Kp and in the adaptation (see chapter 4.4,
page 219).
93
SIPART DR22 6DR2210
C79000-G7476-C154-03