Vdc Control - Siemens SINAMICS S120 Function Manual

5.9

Vdc control

The "Vdc control" function can be activated using the appropriate measures if an overvoltage
or undervoltage is present in the DC link.
● Overvoltage in the DC link
– Typical cause
– Remedy
● Undervoltage in the DC link
– Typical cause
– Remedy
Note
During operation of the Braking Module, the following must be observed:
• You must set the threshold of the Braking Module below the V
• You must switch off the V
Properties
● V
– This comprises V
– Joint PI controller. The dynamic factor is used to set V
● V
– This function can be used to control momentary regenerative load without shutdown
– V
● V
– With this function, the kinetic energy of the motor is used for buffering the DC link
Drive functions
Function Manual, 11/2017, 6SL3097-4AB00-0BP5
The drive is operating in regenerative mode and is supplying too much energy to the
DC link.
Reduce the regenerative torque to maintain the DC link voltage within permissible
limits. With the Vdc controller activated, the converter automatically partly extends the
ramp-down time of a drive if the shutdown supplies too much energy to the DC link.
Failure of the supply voltage or supply for the DC link.
Specify a regenerative torque for the rotating drive to compensate the existing losses,
thereby stabilizing the voltage in the DC link (kinetic buffering).
control
dc
dc_max
independent of each other.
independently of each other.
control
dc_max
using "overvoltage in the DC link".
control is only recommended with a supply without active closed-loop control
dc_max
for the DC link and without feedback.
control (kinetic buffering)
dc_min
voltage in the event of a momentary power failure, thereby delaying the drive.
controller.
dc_max
control and V control (kinetic buffering), which are
dc_min
Vector control
5.9 Vdc control
threshold.
dc_max
and V control
dc_min dc_max
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