Vector V/f control (r0108.2 = 0) 5.4 Vdc control

Reduce the regenerative torque to maintain the DC link voltage within permissible limits.

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 controllers. The dynamic factor is used to set Vdc_min and Vdc_max control to a smoother or harder setting independently of each other.

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.

Vdc_max control

This function can be used to control momentary regenerative load without shutdown with “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.

Description of Vdc_min control

 

3RZHUIDLOXUH

3RZHUUHVWRUH

 

U

 

 

ZLWKRXW.,3IDXOW)

 

9

W

 

 

9

FWUODFWLYH 

 

GF



 

 

 

 

 

W

 

QVHWS

 

 

PLQ

ZLWKRXWSRZHUUHVWRUHIDXOW)

 

 

 

73RZHUIDLOXUH

W

 

 

Figure 5-7 Switching Vdc_min control on/off (kinetic buffering)

176

Drive Functions

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

Page 176
Image 176
Efficient Networks S120 manual Switching Vdcmin control on/off kinetic buffering, Plq