Vdc Control - Siemens SINAMICS S150 Operating Instructions Manual

9.3.3

Vdc control

Description
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 (not relevant to S150).
● Undervoltage in the DC link
Features
● Vdc control
● Vdc_min control (kinetic buffering)
● Vdc_max control (not relevant to S150).
Drive converter cabinet units
Operating Instructions, 07/07, A5E00288214A
– Typical cause:
Failure of the supply voltage or infeed for the DC link.
– Remedy:
Specify a regenerative torque for the rotating drive to compensate the existing losses,
thereby stabilizing the voltage in the DC link This process is known as kinetic
buffering.
Kinetic buffering is only possible as long as energy is generated by the movement of
the drive.
– This comprises Vdc_max control and Vdc_min control (kinetic buffering), which are
independent of each other.
– It includes a joint PI controller. The dynamic factor is used to set Vdc_min and
Vdc_max control to a smoother or harder setting independently of each other.
– With this function, the kinetic energy of the motor is used for buffering the DC link
voltage in the event of a momentary power failure, thereby delaying the drive.
– The motor is ramped up to its setpoint and continues to operate.
Functions, monitoring, and protective functions
9.3 Drive functions
315