KEB COMBIVERT F5-A, Applications Manual, Page: 409 / 552

Protective functions
© KEB, 2012-10 COMBIVERT F5-A, -E, -H Page 7.13 - 35
7
Power off controller (not for vector controlled operation with DSM)
There are two controllers: the DC-link voltage controller and the active current controller.
In v/f-characteristic operation the active current controller is subsequently connected to the DC link voltage
controller.
In vector controlled operation, the output of the DC link voltage controller is used as the torque limit.
If the braking torque is selected as the setpoint (Pn.44 bit 6...7 = 3), the DC link voltage controller is deactivated.
Setpoint = start voltage (Pn.44 Bit 6...7 = 0)
The initial voltage value selected with Pn.44 bit 1 is the setpoint of the DC link voltage controller (see also:
tripping of Power-Off
This setting is used to bridge voltage drops. At power recovery, the drive restarts if the output speed is not yet
fallen below the "power off restart level" (Pn.48).
Setpoint = braking torque (Pn.47; Pn.44 Bit 6...7 = 3) (only v/f characteristic operation)
The braking torque can be preset within the range of 0.0...100.0 %.
The braking torque is used as setpoint source, if the drive must be stopped as fast as possible in case of po-
wer failure. The DC link voltage controller is switched off in this case. Since the DC link voltage increases very
strongly in this mode, a braking module is required.
Since the hardware current limit should not be reached with active current control, the setpoint value is limited
internally which can lead to oscillations. In that case the setpoint value can be reduced, which leads to prolon-
gation of the delay. If the voltage stabilization is switched on (Pn.44 bit 8 = "1") and uF.09 = rated voltage is
adjusted, the voltage is not very high and the deceleration is more evenly.
Setpoint = voltage setpoint (Pn.50; Pn.44 Bit 6...7 = 1 or 2) (only v/f characteristic operation)
The setpoint DC-link voltage can be preset in the range of 200...1200 V. The internal value is limited down in
order to ensure a safe operation. The value of the DC-link voltage in normal operation plus approx. 50V adjusts
itself as minimum value. If a braking resistor is connected, the adjusted value may not lie above the threshold
of the braking resistor, else the controller cannot work (threshold 200V-class: 380V; 400V-class: 740V; 600V-
class: 1140V).
If Pn.44 Bit 6...7 = 1, the voltage setpoint is used as setpoint immediately after the triggering of power off. A
restart is only possible in this mode after reaching the standstill.
In mode Pn.44 Bit 6...7 = 2, initial voltage is adjusted to first after triggering. On undershooting the restart value
(Pn.48), the setpoint is increased to the voltage setpoint (Pn.50) with a ramp. This ensures that the drive upon
reaching the standstill in critical applications has enough energy for braking.
KP DC link voltage controller (Pn.51), KI DC link voltage controller (Pn.57),
To be able to adapt the drive individually to the application, the proportional factor of the DC link voltage con-
troller can be adjusted with Pn.51 and the integral factor with Pn.57, in the range of 0...32767. In most cases
the default setting will achieve sufficient results.
If, however, overshoots or fall backs of the motor occur, the
values must be lowered.
KP (Pn.53), KI (Pn.54), KD (Pn.55) (only V/F characteristic operation)
Pn.53, Pn.54 and Pn.55 are the controller parameters of the active current controller
A D-part usually has a positive effect in the control. Pn.55 should have about 10-times the value of Pn.53.