Danfoss MCO 305 Design Manual page 211

MCO 305 Design Guide
32-63 Limit Value for Integral Sum
KILIM
Range
0 – 1000
0 = Integral off
Function
This parameter limits the integral sum in order to
avoid instability and PID wind-up in case of feed-
back error.
32-64 PID Bandwidth
BANDWIDTH - 35
Range [unit]
0 – 1000 [1/10 %]
0 = PID off
Function
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.
The bandwidth in which the PID controller should
function can be limited, for example to avoid the
built-up of a vibration in case of a system which
could be jeopardized by vibrations.
However, then it is necessary to enter considerably
higher values for the parameters 32-65 Velocity
and 32-66 Acceleration Feed-forward 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 uncontrolled vibrations.
32-65 Velocity Feed-forward
FFVEL
Range
0 – 100000
Function
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.
Velocity Feed-forward indicates the value with
which the velocity forward feed is completed.
default setting
__ Parameter Reference __
1000
1000
[ ] value for use in communication via serial communication port
®
MG.33.L5.02 – VLT is a registered Danfoss trademark
When working with a normal PID algorithm the
FFVEL must always be the same as the D factor in
order to achieve typical dampening D.
32-66 Acceleration Feed-forward
FFACC
Range
0 – 100000
Function
Set the base acceleration whenever you have
limited the bandwidth. Thus you will prevent the
control from not accelerating at all due to the limit
set. Acceleration Feed-forward indicates the value
with which the acceleration forward feed is
completed.
For a normal PID algorithm this value is equal to 0.
32-67 Max. Tolerated Position Error
POSERR
Range [unit]
1 – MLONG [qc]
Function
The Maximum Tolerated Position Error defines the
tolerance allowed between the current actual
position and the calculated command position. If
the value defined with POSERR is exceeded then
the position control is turned off and a position
error is triggered.
The Position Error does not affect the positioning
accuracy, but merely determines how precisely the
theoretically calculated path of motion must be
followed, without an error being triggered.
NB!:
For safety reasons the Position Error
selected should not be too large since this
could be dangerous for both the machine
and its operator.
0
NB!:
On the other hand, if the values for the
Maximum Tolerated Position Error are too
small this could result in frequent errors.
As a guideline, it is wise to set the quadruple of
encoder counts per revolution. This corresponds to
one encoder rotation.
0
20000
211