ABB ACS880 ESP, Firmware Manual

Page: 61 / 494

Standard programposi features 61
Autotune modes
Autotuning can be performed in three different ways depending on the setting of
parameter
25.34 Speed controller autotune mode . The selections Smooth , Normal
and Tight define how the drive torque reference should react to a speed reference
step after tuning. The selection Smooth will produce a slow but robust response;
Tight will produce a fast response but possibly too high gain values for some
applications. The figure below shows speed responses at a speed reference step
(typically 1…20%).
Autotune results
At the end of a successful autotune routine, its results are automatically transferred
into parameters
• 25.02 Speed proportional gain (proportional gain of the speed controller)
• 25.03 Speed integration time (integration time of the speed controller)
• 25.37 Mechanical time constant (mechanical time constant of the motor and
machine).
Nevertheless, it is still possible to manually adjust the controller gain, integration time
and derivation time.
A: Undercompensated
B: Normally tuned (autotuning)
C: Normally tuned (manually). Better dynamic performance than with B
D: Overcompensated speed controller
%
t
n
C
B
D
n
N
A