Parameter descriptions
7.8.1 Dynamic voltage pre-control
605 Dyn. Voltage Pre-Control
The
Dyn. Voltage Pre-Control 605 accelerates the control behavior of the current limit controller
(parameter
Operation Mode 610) and of the voltage controller (parameter Operation Mode 670).
The output voltage value resulting from the V/F characteristic is changed by addition of the calculated
voltage pre-control.
7.9 Control functions
With the control function the control reactions can be set up fitting to the application.
7.9.1 Intelligent current limits
573 Operation Mode (intelligent current limits)
T
he current limits to be set according to the application avoid inadmissible loading of the connected
load and prevent a fault switch-off of the frequency inverter. The function extends the current control-
ler available in the control system. The overload reserve of the frequency inverter can be used opti-
mally by means of the intelligent current limits, in particular in applications with dynamic load
al
-t
ernations. Parameter
Operation Mode 573 defines the threshold to the activation of the intelligent
current limit. The parameterized rated motor current or the reference current of the frequency invert-
er is synchronized as the limit value of the intelligent current limits.
I
n the control method according to V/f-characteristic (setting 110 of
Configuration 30) the intelligent
current limits take effect to the current limit controller. The intelligent current limits are active only in
the case of an active current limit controller.
In the field-orientated control (setting 410 or 610 of
Configuration 30) the maximum torque-forming
current is limited by the intelligent current limits.
0 -
Off The function is switched off.
1 -
Ixt Limitation to the overload of the frequency inverter (Ixt).
Limitation to the maximum heat sink temperature (T
C
).
Operation mode 1 and 10 (Ixt + T
C
).
Limitation to the motor temperature (T
Motor
).
Operation mode 20 and 1 (T
Motor
+ Ixt).
Operation mode 10 and 20 (T
C
+ T
Motor
).
31 -
Tc + Motor Temp. + Ixt
Operation mode 10 and 20 (T
C
Motor
In the operation modes with overload reserve (Ixt) there is a reduction of the output current when the
threshold value is exceeded, with a distinction being made between long and short-term overload
reserve. After the short-term overload (1 s) has been used up, the output current is reduced to the
long-term overload current matching the present switching frequency. After the long-term overload
current has been used up (60 s), the output current is reduced to the rated current which also de-
pends on the switching frequency.
If the output current has already been reduced due to the fact that the long-term overload has used
up, the short-term overload is no longer available even if it has not been used up beforehand. The
defined overload reserve (Ixt) of the frequency inverter is available again after a power reduction
lasting 10 minutes.
213
Control functions 06/2013 Operating Instructions
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