Danfoss MCO 305 Operating Instructions Manual page 33

MCO 305 Operating Instructions
9. Reduce the par. 32-64 PID Bandwidth as much as possible. With a properly optimized open-loop control
Bandwidth could be reduced to as little as 6 or 12 % (60 – 120).
10. Set the par. 32-67 Position Error back to normal e.g. 20,000.
11. Once you have concluded the Testrun then
these parameters are saved in the controller and in the future will be used for all programs.
What to do if . . . ?
What to do, if there is a tendency towards instability?
In the event of a strong tendency towards instability reduce the parameters 32-60 and 32-61 Proportional
and Derivative Factors again, or reset the par. 32-62 Integral Factor.
What to do, if stationary precision is required?
If stationary precision is required then you must increase the par. 32-62 Integral Factor.
What to do if the tolerated position error is exceeded?
If the test run is constantly interrupted with the message "position error" set the par. 32-67 Maximum
Tolerated Position Error– within the tolerable limits– as large as possible.
If the position error occurs during the acceleration phase that suggests that the set acceleration cannot be
achieved under the existing load conditions. Increase the par. 32-67 Position Error or determine a Maximum
Acceleration suitable for the entire system.
If position errors do not occur until after the acceleration phase and they can be delayed but not eliminated
by increasing the 32-67 Max. Tolerated Position Error, this suggests that the Maximum Velocity (RPM)
chosen is too high. Determine a maximum velocity suitable for the entire system.
What to do if the maximum acceleration is not achieved?
In general, the technical data for a drive are only valid for a freely rotating axle end. If the drive is carrying
a load the maximum acceleration is reduced.
The theoretical maximum acceleration will also not be achieved if, for example, the PID controller output is
too small or the FC 300/motor is not sized correctly and therefore does not provide enough energy for peak
consumption during acceleration.
__ Optimizing the PID Controller __
Save the new parameters as the user parameters. Thus,
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