KEB COMBIVERT F5-A, Руководство по применению, Страница: 448 / 552

Page 7.15 - 16 COMBIVERT F5-A, -E, -H © KEB, 2012-10
Special functions
7.15.5.4 Brake control / vector controlled
Premagnetisation and delay time
In vector controlled operation, the drive also builds up torque at setpoint speed 0. Therefore, no start or stop
speed is required (Pn.37 = Pn.41 = 0 rpm).
Thus also the premagnetizing time Pn.35 can be set to zero.
The time the drive requires for flux build-up is
always await, until the output for brake release is set.
Exception:
If the bit 7 "wait for magnetisation" in dS.04 "Flux- / rotor adaptions mode" is set to "0: off", a pre-magnetisation
time must be parametrised for flux build-up. This setting is permissible only for operation without motor model.
Since, independent of the selected deceleration ramp, the brake closing time only starts when the actual speed
reaches the value of the stop speed (= 0 rpm), no brake delay time has to be awaited.
In some applications, however, the brake delay time is used to save time.
If the output for brake control has been deactivated once, the complete brake handling (brake closing time +
fadeout time + brake opening time) must be executed for a new start of the drive.
By setting a brake delay time, the collapse of the brake can be suppressed for a quick succession of starts (e.g.,
for positioning). Only when the drive remains stationary for a longer period, the brake is closed.
Optimization of the load transfer
In vector controlled operation, there are another two special functions that optimise the load transfer to the
drive:
•
speed-dependent Ki for the speed controller
For the load transfer, an enormous speed rigidity is often required for hoists or lifts so that the opening
of the brake and the transfer of the load by the inverter is not felt. This rigidity can be achieved by a very
large "K-increase" (cS.10) for the speed controller.
This increase is normally reversed again over an adjustable speed range. For extremely large KI-incre-
ases, this slow reversal cannot be used since the speed controller is then too vibration-prone.
By input of the value "-1: Brake release" in parameter corner speed for max. KI (cS.11), one can achieve
that the "KI-increase" is immediately set to 0 at the end of the brake opening time.
•
Brake precontrol
Without precontrol, the drive must first move, i.e., a system deviation must be built up so that the control
-
ler provides a counter torque.
With the precontrol, the speed controller is preloaded with a torque at the beginning of the brake opening
time. To avoid "stall out", this torque is, in the ideal case, equal to the load to be taken over by the brake.
The precontrol value is set with a ramp within 1/5 of the brake ventilation time.
The function is activated by selecting in Pn.70 "brake pretorque source" how the precontrol value is to
be defined.
Pn.70: Brake pretorque source
Value Function
0: off Precontrol function off
1: analog REF
Setting of the precontrol torque in % of the rated torque via the analog channel REF or
AUX. The analog signal can come from, e.g., a load weighing setup in a lift cabin.
2: analog Aux
3: digital % (Pn.71)
Setting of the precontrol torque in % of the rated torque via parameter Pn.71 "Brake
precontrol setpoint in %"
Example: Let a lift be equipped with a counterweight so that for a half-loaded cabin, no holding torque
must be expended.
For an empty cabin, the load weighing setup provides a signal of 0%.