ABB ACS850 - Page 219

Parameters 219
40.03 Slip gain Defines the slip gain which is used to improve the estimated
motor slip. 100% means full slip gain; 0% means no slip gain.
The default value is 100%. Other values can be used if a
static speed error is detected despite of the full slip gain.
Example (with nominal load and nominal slip of 40 rpm): A
1000 rpm constant speed reference is given to the drive.
Despite of the full slip gain (= 100%), a manual tachometer
measurement from the motor axis gives a speed value of 998
rpm. The static speed error is 1000 rpm - 998 rpm = 2 rpm. To
compensate the error, the slip gain should be increased. At
the 105% gain value, no static speed error exists (2 rpm / 40
rpm = 5%).
0 … 200% Slip gain. 1 = 1%
40.04 Voltage reserve Defines the minimum allowed voltage reserve. When the
voltage reserve has decreased to the set value, the drive
enters the field weakening area.
If the intermediate circuit DC voltage U
dc
= 550 V and the
voltage reserve is 5%, the RMS value of the maximum output
voltage in steady-state operation is
0.95 × 550 V / sqrt(2) = 369 V
The dynamic performance of the motor control in the field
weakening area can be improved by increasing the voltage
reserve value, but the drive enters the field weakening area
earlier.
-4 … 50% Voltage reserve. 1 = 1%
40.06 Force open loop Defines the speed/position information used by the motor
model.
False Motor model uses the speed feedback selected by parameter
19.02 Speed fb sel.
0
True Motor model uses the internal speed estimate (even when
parameter 19.02 Speed fb sel is set to Enc1 speed / Enc2
speed).
1
No. Name/Value Description FbEq