SKS Sweden Bonfiglioli Vectron ACTIVE CUBE ACU 201 Series, Operating Instructions Manual

Page: 197 / 260

09/08
Operating Instructions ACU
195
The behavior of the technology controller corresponds to a PID controller with the
components
− proportional component
Amplification
444
− integral component
Integral time
445
− differential component
Derivative time
618
The sign of the amplification determines the direction of control, i.e. with a rising
actual value and pos. sign of the amplification, the output frequency is reduced (e.g.
in pressure control). With a rising actual value and neg. sign of the amplification, the
output frequency is increased (e.g. in temperature control systems, refrigerating
machines, condensers).
The integral component can be used to reduce the steady-state control deviation
(deviation between actual value and reference value) over a period of time. If the
integral component is too dynamic
1)
the system will be unstable and oscillates. If the
integral component is too passive
2)
the steady-state control deviation will not be cor-
rected adequately.
Therefore the integral component must be adjustet installation-dependent.
1)
Dynamic behavior: fast correction of deviations.
2)
Passive behavior: slow correction of deviations.
In the factory setting
Derivative time
618 = 0 ms the differential component is dis-
abled.
If the control behavior of the PI controller (or P controller) is too slow the setting of
the differential component (
Derivative time
618) allows a faster control. If the diffe-
rential component is enabled the system tends to oscillate, so that the differential
component should be enabled and set carefully.
BONFIGLIOLI VECTRON recommends to set the values of
Integral time
445 and
Derivative time
618 higher than the sample time, which is 2 ms at the ACU device.
Parameter
Max. P-Component
442 limits the frequency change at the controller
output. This prevents oscillations of the system at steep acceleration ramps.
Via Parameter
Hysteresis
443 changes of the integral component in a specified
range (hysteresis band) can be rejected. This causes more passiv behavior of the
technology controller and helps to filter noise signals of the controller actual value
and to minimize control corrections.
f
t
Hysteresis
443
Parameter Settings
No. Description Min. Max. Fact. sett.
441 Fixed Frequency -999.99 Hz +999.99 Hz 0.00 Hz
442 Max. P-Component 0.01 Hz 999.99 Hz 50.00 Hz
443 Hysteresis 0.01 % 100.00 % 10.00 %
444 Amplification -15.00 +15.00 1.00
445 Integral Time 0 ms 32767 ms 200 ms
446 Ind. Volume Flow Control Factor 0.10 2.00 1.00
618 Derivative Time 0 ms 1000 ms 0 ms
Operating Instructions ACU 195 09/08