Danfoss VLT AutomationDrive FC 301 Programming Manual page 53

Parameter Descriptions
1-80 Function at Stop
Option: Function:
Sample rotor time constants =
(Xh+X2)/(6.3*Freq_nom*Rr)
1 kW = 0.2 s
10 kW = 0.5 s
100 kW = 1.7 s
1000 kW = 2.5 s
[4] DC Voltage When the motor is stopped, the
U0 parameter 1-55 U/f Characteristic - U [0]
defines the voltage at 0 Hz.
1-81 Min Speed for Function at Stop [RPM]
Range: Function:
Size related [0 - 600 Set the speed at which to activate
*
RPM] parameter 1-80 Function at Stop.
1-82 Min Speed for Function at Stop [Hz]
Range: Function:
Size related [ 0 - 20.0 Set the output frequency at which to
*
Hz] activate parameter 1-80 Function at
Stop.
1-83 Precise Stop Function
Option: Function:
NOTICE
This parameter cannot be adjusted while
the motor is running.
Valid for FC 302 only.
[0] Precise Only optimal when the operational speed, for
ramp example the operational speed of a conveyor belt,
*
stop is constant. This is an open-loop control. Achieves
high repetitive precision at the stop point.
MG33MO02
Programming Guide
•
Set parameter 1-71 Start
Delay to the required
premagnetizing time (2–4
rotor time constants. See
the time constants
description further in this
section).
•
Set parameter 1-72 Start
Function to either [0] DC
hold or [1] DC Brake.
•
Set the DC hold or DC
brake current magnitude
(parameter 2-00 DC Hold
Current or
parameter 2-01 DC Brake
Current) to be equal to
I_pre-mag = Unom/(1.73 x
Xh)
Danfoss A/S © 01/2018 All rights reserved.
1-83 Precise Stop Function
Option: Function:
[1] Cnt stop Counts the number of pulses, typically from an
with encoder, and generates a stop signal after a pre-
reset programmed number of pulses, defined in
parameter 1-84 Precise Stop Counter Value, has
been received at terminal 29 or terminal 33.
This is direct feedback with one-way closed-loop
control.
The counter function is activated (starts timing) at
the edge of the start signal (when it changes from
stop to start). After each precise stop, the number
of pulses counted during ramp down to 0 RPM is
reset.
[2] Cnt stop Same as [2] Cnt stop with reset but the number of
w/o pulses counted during ramp down to 0 RPM is
reset deducted from the counter value entered in
parameter 1-84 Precise Stop Counter Value.
This reset function can be used to compensate for
the extra distance done during ramping down
and to reduce the impacts of gradual wear of
mechanical parts.
[3] Speed Stops at precisely the same point, regardless of
comp the present speed. The stop signal is delayed
stop internally when the present speed is lower than
the maximum speed (set in parameter 4-19 Max
Output Frequency).
The delay is calculated on the basis of the
reference speed of the frequency converter and
not on the basis of the actual speed. Make sure
that the frequency converter has ramped up
before activating the speed compensated stop.
[4] Com cnt Same as Speed comp stop but after each precise
stop stop, the number of pulses counted during ramp
w/rst down to 0 RPM is reset.
[5] Comp Same as Speed comp stop but the number of
cnt stop pulses counted during ramp down to 0 RPM is
w/o r deducted from the counter value entered in
parameter 1-84 Precise Stop Counter Value.
This reset function can be used to compensate for
the extra distance done during ramping down
and to reduce the impacts of gradual wear of
mechanical parts.
The precise stop functions are advantageous in
applications where high precision is required.
If using a standard stop command, the accuracy is
determined by the internal task time. That is not the case
when using the precise stop function. It eliminates the task
time dependence and increases the accuracy substantially.
The frequency converter tolerance is normally given by its
task time. However, by using its special precise stop
function, the tolerance is independent of the task time
because the stop signal immediately interrupts the
execution of the frequency converter program. The precise
stop function gives a highly reproducible delay from the
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