Efficient Networks S120 manual Properties

Vector control 4.9 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

The drive is operating in regenerative mode and is supplying too much energy to the DC link.

–Remedy

Reduce the regenerative torque to maintain the DC link voltage within permissible limits. With the Vdc controller activated, the converter may automatically extend the ramp down time of a drive if the shutdown supplies too much energy to the DC link.

●Undervoltage in the DC link

–Typical cause

Failure of the supply voltage or supply 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 (kinetic buffering).

Properties

●Vdc control

–This comprises Vdc_max control and Vdc_min control (kinetic buffering), which are independent of each other.

–Joint PI controller. The dynamic factor is used to set Vdc_min and Vdc_max control independently of each other.

●Vdc_max control

–This function can be used to control momentary regenerative load without shutdown using “overvoltage in the DC link“.

–Vdc_max control is only recommended with a supply without active closed-loop control for the DC link and without feedback.

●Vdc_min control (kinetic buffering)

–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.

134	Drive Functions
	Function Manual, (FH1), 07/2007 Edition, 6SL3097-2AB00-0BP4