Danfoss VLT 5000 Series Manual page 141

34 DFLTACC
DFLTACC indicates the acceleration used when no
explicit statements have been made. This state-
ment is made in relation to RAMPMIN (31) and
refers to the VELRES (22) parameter.
Content
Default acceleration
Parameter Group
AXV
Unit
1 /
VELRES;
1
Standard = / = %
100
Value range
1 ... VELRES
3 5 BANDWIDTH (706)
You can limit the bandwidth in which the PID con-
troller should function, for example to avoid the
built-up of a vibration if you are operating a system
which could be jeopardized by vibrations.
However, then it is necessary to enter considerably
higher values for the parameters FFVEL (36) and
FFACC (37) in order to achieve the corresponding
control. A system adjusted in such a manner is not
as dynamic as it could be, but is considerably
more stable and tends to experience less uncon-
trolled vibrations.
Content
Bandwidth within which the PID filter is active
Parameter Group
AXR
Unit
%
The value 1000 means that the PID filter can out-
put the full command value. For a BANDWIDTH of
500 only 50 % of the set value is output. Thus,
values less than 1000 limit the P-share accordingly.
Value range
0 ... 1000
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VLT 5000 SyncPos option
36 FFVEL (707)
When a control has a limited bandwidth then a
base velocity must be set so that it can be ruled
out that the control will entirely prevent the drive
from running due to the limit set. FFVEL indicates
the value with which the velocity feed-forward is
completed.
When working with a normal PID algorithm the
FFVEL must always be the same as the KDER
factor in order to achieve typical dampening.
Content
Velocity feed-forward
Parameter Group
AXR
Unit
# 50
%
Value range
0 ... 65000
37 FFACC (708)
Set the base velocity whenever you have limited
the bandwidth. Thus you will prevent the control
from not accelerating at all due to the limit set.
FFACC indicates the value with which the accele-
ration feed-forward is completed.
For a normal PID algorithm this value is equal to 0.
Content
Acceleration feed-forward
Parameter Group
AXR
Unit
%
Value range
0 ... 65000
# 1000
# 0
# 0
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