Using the test run functions can optimise the PID factors further:
There is two types of test run available: Positioning where the slave drive moves a specific distance
and synchronising with virtual master where the slave follows the virtual master in position or
speed. Generally it is better to use test run with virtual master as that comes closer to the operating
conditions in synchronising mode (program 2).
For test run with positioning the following parameters must be set:
Parameter No. 19-01
Test run speed: Record the speed as a percentage of the maximum speed of parameter 3280.
Parameter No. 19-02
Test run acceleration: record the acceleration time in per cent. 100% is minimum acceleration.
50% is half as fast as minimum acceleration, the ramp time will thus be twice as long.
Parameter No. 19-03
Test run distance: Record the distance (quad counts) for the drive to run during optimisation.
Then use the following procedure:
1.
Close the contacts at terminal 32 (clockwise direction) or terminal 33 (counter-clockwise).
During the test the last value of the first display line will indicate the track error (PID
error). After the test run is completed you can see the maximum track error (PID error).
2.
Increase the P-portion (par. 3260). After each change you should make a test run to find
the right setting. If the drive becomes unsteady or if a message is given about over-
voltage or over-current, then reduce the value in parameter 3260 to about 70-80% of
the set value.
3.
Now set the D-portion (parameter 3261) to 5 times the value of parameter 3260.
4.
If a lower synchronising error is required the I-portion (parameter 3262) can be set to a
low value e.g. 10 but be careful a too high value will course overshoot and instability
F
or test run with virtual master the following parameters must be set:
Parameter No. 19-16
Virtual master reference: Select the reference source for setting the velocity of the virtual master.
“0” is analogue input 53, “1” is parameter 310 sub-index, “2” is Fieldbus PCD 2.
Parameter No. 19-17
Virtual master acceleration: Set the acceleration of the virtual master in encoder pulses per sec-
ond
2
.
Parameter No. 19-18
Virtual master maximum speed: Set the maximum velocity of the virtual master in encoder pulses
per second.
Then use the following procedure:
1.
Start test run with virtual master by activating input 3. During test run you can read the
track error in the last value of the first display line. At stop the maximum track error
during the test run is read out.
2.
If more accurate and dynamic control is required the P-portion (parameter 3260) must
be increased. If the slave becomes unstable the value must be reduced to by approxi-
mately 25%.
3.
Now set the D-portion (parameter 3261) to 5 times the value of parameter 3260.
4.
If a lower synchronising error is required the I-portion (parameter 3262) can be set to a
low value e.g. 10 but be careful a too high value will course overshoot and instability.
4. Synchronisation
Syncronising Controller MCO 350 Operating
Instructions
76
MG.33.Q1.02 - VLT
®
is a registered Danfoss trademark
4
