Danfoss MCO 305 Design Manual page 224

MCO 305 Design Guide
33-25 Marker Number for Ready
SYNCREADY
Range
0 – 10000
Function
SYNCREADY defines how often during a marker
synchronization (SYNCM and SYNCCMM) a synchro-
nization evaluation with ACCURACY must be
completed with accuracy so that ready is fulfilled.
ACCURACY is checked during every correction. If
ACCURACY is fulfilled then 1 is added until the set
marker number has been achieved.
Synchronization evaluation is always executed after
m marker pulses by the master par. 33-15 Marker
Number for Master.
ACCURAY and READY can be queried using SYNCSTAT.
33-26 Velocity Filter
SYNCVFTIME
Range [Unit]
–MLONG – MLONG [μs]
–999 – 999 = standard table
Standard Table
encoder resolution τ_filt [μs]
250
256
500
512
1000
1024
2000
2048
2500
4096
5000
Function
This parameter configures the velocity filter which is
used for the velocity synchronization. Since the ve-
locity synchronization only uses the currently active
master velocity and the values can decrease to very
small values (e.g. 2 qc/ms), a small fluctuation in
velocity can have dramatic effects. In order to even
this out the following filter function is applied:
Cmdvel =
Old_Cmdvel + (Actvel – Old_Cmdvel) * ms/τ_filt
default setting
224
__ Parameter Reference __
39500
38600
19500
19000
9500
9300
4500
4400
3500
1900
1400
[ ] value for use in communication via serial communication port
®
MG.33.L5.02 – VLT is a registered Danfoss trademark
With the following:
Cmdvel = set velocity
Old_Cmdvel = last set velocity
Actvel = actual velocity of the master
ms = sampling time (fixed 1ms)
1
τ_filt = filter time constants
Generally the value for τ_filt is taken from a table,
depending on the Encoder counts per revolution of
the master. This value can be overwritten by the
parameter Velocity Filter and is always used when
Velocity Filter is not equal zero.
If the speed filter is defined with a negative
number, the corresponding value also applies for
angle/position synchronization SYNCP and for
marker correction SYNCM.
In this case filtering takes place as described
above, but the errors made are summed up. This
error sum is taken into the calculation with
1000/(τ*10) in each case, so that no position
deviation can occur over prolonged periods.
The value returned by SYNCERR always contains
the error made so that this is also used for the eva-
luation of the synchronicity. In the case of marker
correction the correction value is balanced more
0
slowly and with the same factor as the error sums.
If, for example, a filter factor of –100000 (100 ms)
is used, a marker correction is balanced within
1 second (100 ms * 10). This allows a 'taming' of the
synchronization without restricting the acceleration.
33-27 Offset Filter Time
SYNCOFFTIME
Range [Unit]
0 – MLONG [ms]
Function
Compensation velocity of an offset (1. synchronize;
2. new offset)
The Offset Filter Time also influences the way, how
a new Position Offset for Synchronization (par. 33-
12) value is handled. The offset which has to be
realized will be done step by step. The step which
is realized every sample time (ms) is calculated as
follows:
par. 33
step size =
par. 33 - 27
So it will take Offset Filter Time to realize an offset
of par. 33-17 Master Marker Distance. The Offset
Filter Time also has influence on the marker start
correction and on the correction of marker error
(see par. 33-29 Filter Time for Marker Correction).
- 17 Master Marker Distance
Offset Filter Tim e (integer part)
0