Kinetic Buffering (Vdc Min Control) - Siemens SINAMICS G120 Operating Instructions Manual

Advanced commissioning

6.31 Kinetic buffering (Vdc min control)

6.31 Kinetic buffering (Vdc min control)
Kinetic buffering increases the drive availability. The kinetic buffering utilizes the kinetic energy
of the load to buffer line dips and failures. During a line dip, the inverter keeps the motor in the
switched-on state for as long as possible. One second is a typical, maximum buffer time.
Preconditions
The following prerequisites must be fulfilled to practically use the "kinetic buffering" function:
● The driven load has a sufficiently high inertia.
● The application allows a motor to be braked during a power failure.
The Vdc_min control is only possible with PM240-2 Power Modules.
Function
When the line supply dips or is interrupted, the DC link voltage in the inverter decreases. At
an adjustable threshold, kinetic buffering intervenes (V
the load to go into slightly regenerative operation. As a consequence, the inverter covers its
power loss and the losses in the motor with the kinetic energy of the load. The load speed
decreases; however, during kinetic buffering, the DC voltage remains constant. After the line
supply returns, the inverter immediately resumes normal operation.
Figure 6-74
Parameter
r0056.15
p0210
350
Principle mode of operation of kinetic buffering
Description
Status word closed-loop control
0 signal V controller is not active
DC min
1 signal V controller is active (kinetic buffering)
DC min
Device supply voltage (factory setting: 400 V)
control). The V
DC min
Converter with the CU250S-2 Control Units
Operating Instructions, 04/2018, FW V4.7 SP10, A5E31759476B AG
control forces
DC min