Efficient Networks S120 Description of Vdcmin control p1240 = 2, 3RZHUIDLOXUH 3RZHUUHVWRUH

Servo control 3.14 Vdc control

significant enough. The motors may no longer be able to maintain their setpoint speed or the acceleration/braking phases are prolonged.

The Vdc controller is an automatic P controller that influences the torque limits. It only intervenes when the DC link voltage approaches the "upper threshold" (p1244) or "lower threshold" (p1248) and the corresponding controller is activated via the configuration parameter (p1240).

The recommended setting for the P gain is p1250 = 0.5*DC link capacitance [mF].

Once the DC link has been identified (p3410), the DC link capacitance can be read in parameter p3422 in the Infeed Module.

Note

To ensure that the drives remain active if the Line Module has failed, the response to fault F07841 must be changed to "none" or the operation message from the Infeed Module must be permanently set to "1" with p0864.

The Vdc controller can be used, for example, when a Line Module without energy feedback (Vdc_max controller) is used and as a safety measure in the event of a power failure (Vdc_min and Vdc_max controller). To ensure that critical drives can be operated for as long as possible, parameterizable faults exist that switch off individual drives if there is a problem with the DC link.

Description of Vdc_min control (p1240 = 2, 3)

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Figure 3-21 Switching Vdc_min control on/off (kinetic buffering)

In the event of a power failure, the Line Module can no longer supply the DC link voltage, particularly if the Motor Modules in the DC link line-up are drawing active power. To maintain the DC link voltage in the event of a power failure (e.g. for a controlled emergency retraction), the Vdc_min controller can be activated for one or more drives. If the voltage threshold set in p1248 is undershot, these drives are decelerated so that their kinetic energy

Drive Functions	103
Function Manual, (FH1), 07/2007 Edition, 6SL3097-2AB00-0BP4