ABB ACS850 series, Manual

Page: 179 / 370

Parameters 179
23.05 Acc comp DerTime Defines the derivation time for acceleration/(deceleration)
compensation. In order to compensate inertia during
acceleration, a derivative of the reference is added to the
output of the speed controller. The principle of a derivative
action is described for parameter
23.03 Derivation time .
Note: As a general rule, set this parameter to the value
between 50 and 100% of the sum of the mechanical time
constants of the motor and the driven machine.
The figure below shows the speed responses when a high
inertia load is accelerated along a ramp.
No acceleration compensation:
Acceleration compensation:
0.00 … 600.00 s Acceleration compensation derivation time. 100 = 1 s
23.06 Acc comp Ftime Defines the derivation filter time constant for the
acceleration(/deceleration) compensation. See parameters
23.03 Derivation time and 23.05 Acc comp DerTime .
Note: This parameter is automatically set by the speed
controller autotune function (when performed in User mode).
See parameter 23.20 PI tune mode .
0.0 … 1000.0 ms Derivation filter time constant for acceleration compensation. 10 = 1 ms
23.07 Speed err Ftime Defines the time constant of the speed error low pass filter.
If the used speed reference changes rapidly, the possible
interferences in the speed measurement can be filtered with
the speed error filter. Reducing the ripple with filter may cause
speed controller tuning problems. A long filter time constant
and fast acceleration time contradict one another. A very long
filter time results in unstable control.
No. Name/Value Description FbEq
Time
%
Speed reference
Actual speed
Time
%
Speed reference
Actual speed