BONFIGLIOLI ACTIVE Cube ACU 401-25 User Manual

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 amplifica
tion, the output frequency is reduced (e.g.
in pressu
re control). With a rising actual value and neg. sign of the amplification, the
output frequency is increased (e.g. in tem
perature 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 adjusted 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 disa-
bled.
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 dif-
ferential component is enabled the system tends to oscillate, so that the
differential
component should be enabled and set carefully.
BONFIGLIOLI VECTRON recommends setting 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 outside
a specified
range (hysteresis band) can be suppressed. This causes more passive
behavior of the
technology controller
. This can be helpful when the stator frequency cannot follow
the reference frequency of the Technology controller. Hysteresis 443
is related to
Rated frequency 375, in most cases therefore 50 Hz.
The hysteresis acts as a limiter at the input of the integral part. Excessive differences
between the stator current and the output of the controller technology are so limited
and so prevent excessive integration of the integral value.
443
375
Hysteresis
frequencyRated
ff
statortech
≥
−
The deviation ∆ between Reference frequency
of the Technology Controller (f
tech
) and Stator
frequency (f
stator
) is too big. The Integrator is
halted.
443
375
Hysteresis
frequenzRated
ff
statortech
<
−
The Stator frequency (f
stator
) can follow the
reference frequency of the technology control-
ler sufficiently. The deviation ∆ is
mall
enough.
218 Operating Instructions ACU 06/13

BONFIGLIOLI ACTIVE Cube ACU 401-25 Specifications

General

Brand	BONFIGLIOLI
Model	ACTIVE Cube ACU 401-25
Category	Inverter
Language	English