Danfoss MCO 305 Design Manual page 228

MCO 305 Design Guide
Function
This parameter supports velocity dependent posi-
tion feed forward in synchronous modes (SYNCP/
SYNCM/ SYNCC).
This parameter is either 0 (disabled), which is
default, or a value which gives the feed forward in
1/1000 of command velocity. That means a value
of 1000 adds a feed forward to MPCMD (sync
command position) of VCMD (command velocity).
To determine the value to use, the sysvar
NORMTRACKERR can be used. If you find out that
your normal NORMTRACKERR is 100 percent, then
you should set the SYNCFFVEL to 1000.
This allows to minimize SYNCERR. With such a feed
forward the sync error could be nearly eliminated
without having the disadvantages of using an INT
part in the PID.
At the moment there is still the disadvantage that
you have a bump if you are starting SYNCP while
running. This occurs if you come up to velocity by a
SYNCC or a CVEL and then start SYNCP.
New sysvar REG_NORMTRACKERR (4124), see also
SDO dictionary, axis process data.
This SYSVAR gives back the track error in relation
to command velocity in percent. For example, a
value of 120 tells you that the track error is 1.2
times VCMD. This value is relatively constant if the
conditions do not change (load, friction, ...). This
value typically is independent of the velocity.
The parameter is available starting with MCO 5.00.
33-33 Velocity Filter Window
SYNCVFLIMIT - 100
Range [qc]
0 ... MLONG
0 = disabled
Function
Sync error window [qc] for automatic deactivation
of 33-26 Velocity Filter SYNCVFTIME.
The Velocity Filter is deactivated, when sync error
exceeds the value given by SYNCVFLIMIT.
The Velocity Filter is activated again, when sync
error decreases below 1/5 of SYNCVFLIMIT.
This parameter helps to avoid big synchronization
errors when master is accelerating or decelerating
and a large value for SYNCVFTIME is used.
default setting
228
__ Parameter Reference __
[ ] value for use in communication via serial communication port
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MG.33.L5.02 – VLT is a registered Danfoss trademark
This parameter allows the deactivation of the par.
33-26 Velocity Filter if the error becomes bigger
than SYNCVFLIMIT. If the filter error
(PFG_G_MFILTERROR) exceeds the value of
SYNCVFLIMIT (qc) then the filter is deactivated
slowly. If the error becomes smaller than
SYNCVFLIMIT/5, then the filter is activated again.
In case of SYNCM, the internal filter error is reset
every SYNCVFTIME to zero because it is only
growing and never decreasing. In that case, after
SYNCVFTIME it is again checked if it is small
enough to reactivate it.
The filter is not disabled or enabled immediately,
but it will be increased or decreased slowly by 1 ms
per ms. And it is not disabled totally, but it is
leaved at least at 5 ms. In the case of SYNCP, the
original filter value is still used to calculate the
actual filter error (PFG_G_MFILTERROR) to decide if
the filter should be enabled again. In the case of
SYNCM (no error correction), the filter error is
reset to zero and is waited at least SYNCVFTIME to
decide if the filter error stays below limit or not. If
it stays below limit, then the filter is activated
again.
The filter error can be observed using the sysvar
PFG_G_MFILTERROR, see also SDO dictionary, axis
process data.
The parameter is available starting with MCO 5.00.
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