Siemens sinamics dcp - Closed-Loop Control

Operation
7.11 Closed-loop control
SINAMICS DCP
344 Operating Instructions, 09/2019, A5E34382853K
Automatic DC link buffering
See function diagrams 6730 and 6819 in the SINAMICS DCP List Manual.
This function is used to supply the DC link of a frequency converter, which is usually fed from
the three-phase line supply via an infeed unit, from a battery if the power fails and, in this
way, to maintain uninterrupted operation of a connected motor.
To do this, a dead range (p54124) is defined symmetrically around the voltage setpoint
(r54103); this means that the DCP voltage controller remains inhibited as long as the voltage
actual value lies in the range between the following limits:
● r54103 + (0.5 × p54124)
● r54103 - (0.5 × p54124)
In this case, the infeed unit controls the DC link voltage. If the voltage actual value leaves the
dead range, then the DCP voltage controller is enabled.
It controls the voltage back to the setpoint and remains enabled until the set minimum time
(p54146) has expired. The voltage controller can also be enabled using BICO input p54145.
● For the factory setting p54124 = 0 %, the automatic DC link buffering is always active; as
a consequence, the voltage controller is always enabled independent of the value of
parameter p54145.
● For p54124 = 100 %, the automatic DC link buffering is deactivated. The voltage
controller can either be enabled or inhibited via BICO (p54145).
● For values of p54124 between 0 % and 100 %, the automatic DC link buffering is enabled
and when required intervenes.
In addition, the voltage controller can also be enabled via BICO (p54145). However, the
voltage controller can only be inhibited if the voltage is within the tolerance range.
Note
To use this funct
ion, p54105 = 1 must be set.
7.11.9 Voltage correction controller
See function diagram 6807 in the SINAMICS DCP List Manual.
The voltage correction controller is used to improve the precision of the voltage control
and/or to compensate the voltage drop across the power cables.
To do this, external voltage measured values can be read-in, and the setpoint for the internal
voltage controller appropriately corrected.
The correction controller is always superimposed on the internal voltage controller and
corrects its setpoint depending on the deviation between the voltage setpoint and external
voltage actual value. This is the reason that the internal voltage control loop is essentially
uninfluenced by the external actual value.