ABB ACS850 series, Manual

Page: 61 / 370

Program features 61
Motor control
„
Constant speeds
It is possible to predefine up to 7 constant speeds. Constant speeds can be activated,
for example, through digital inputs. Constant speeds override the speed reference.
Settings
Parameter group 26 Constant speeds (page 186 ).
„
Critical speeds
A Critical speeds function is available for applications where it is necessary to avoid
certain motor speeds or speed ranges because of, for example, mechanical
resonance problems.
Settings
Parameter group 25 Critical speed (page 185 ).
„
Speed controller tuning
The speed controller of the drive can be automatically adjusted using the autotune
function (parameter
23.20 PI tune mode ). Autotuning is based on the load and inertia
of the motor and the machine. It is, however, also possible to manually adjust the
controller gain, integration time and derivation time.
Autotuning can be performed in four different ways depending on the setting of
parameter
23.20 PI tune mode . The selections Smooth , Middle and Tight define how
the drive torque reference should react to a speed reference step after tuning. The
selection
Smooth will produce a slow response; Tight will produce a fast response.
The selection User allows customized control sensitivity adjustment through
parameters 23.21 Tune bandwidth and 23.22 Tune damping . Detailed tuning status
information is provided by parameter 06.03 Speed ctrl stat . If the autotuning routine
fails, the SPEED CTRL TUNE FAIL alarm will occur for approximately 15 seconds. If
a stop command is given to the drive during the autotuning, the routine is aborted.