Behavior in motor operation:
If the current set via parameter Current limit 613 is exceeded, the acti
vated current
limit value controller will reduce the output frequency until the current limit is no
longer exceeded. The output frequency is reduced as a maximum to the frequency
set by the parameter Frequency limit 614. If the Current limit
613
is fallen short of,
the output frequency is raised back to the reference value.
Behavior in generator operation:
If the current set via parameter Current limit 613
is exceeded, the activated current
limit value controller will increase the output freq
uency until the current limit is no
longer exceeded. The output frequency is increased, as a maximum, to the set Max-
imum frequency
419. If the current is below the Current limit
613, the output fre-
quency is reduced to the required reference value again.
⋅
⋅
The control behavior of the current limit value controller can be set via the propor-
tional component, the parameter Amplification 611
, and the integrating component,
the parameter Integral time
612
. If an optimization of the controller parameters is
necessary in exceptional cases, a setting should be done by a jump alteration of the
parameter Current limit 613.
Parameter Settings
611
Amplification 0.01 30.00 1.00
612
Integral time 1 ms 10000 ms 24 ms
The dynamics of the current limit value controller and the voltage controller is influ-
enced by the setting of the parameter
Dyn. voltage pre-control 605.
17.5 Functions of Field-Orientated Control
The field-orientated control systems are based on a cascade control and the calcula-
tion of a complex machine model. In the course of the guided commissioning, a map
of the connected machine is produced by the parameter identification and transferred
to va
rious parameters. Some of these parameters are visible and can be optimized
for various operating points.
17.5.1 Current Controller
The inner control loop of the field-orientated control comprises two current control-
lers. The field-
orientated control thus impresses the motor current into the machine
via two components to be controlled.
This is done by:
− controlling the flux-forming current value I
sd
− controlling the torque-forming current value I
sq
By separate regulation of these two parameters, a decoupling of the system equiva-
lent to an externally excited direct current machine is achieved.
06/13 Operating Instructions ACU 227
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