ABB ACSM1 Series, Manual

Page: 60 / 510

Drive control and features
60
With absolute encoders and resolvers, there is often a need to change the position
calculation zero permanently without physically rotating the motor. This is possible
by using parameter
62.20 POS ACT OFFSET . The value of the parameter is added
to the position feedback value. The offset can be made permanent after the homing
procedure using parameter
62.21 POS COR MODE .
Position estimation
With synchronous motors, the drive also supports positioning without a speed and
position feedback device. In position estimation, the actual position of the drive (
1.12
POS ACT ) is calculated using the estimated speed as the position change between
the current time and the last known position. The accuracy of this position estimate
depends heavily on the motor model accuracy. The different types of position
scaling, the drive position system range and the hardware limits are the same as for
position calculation.
Position estimation can be selected as the position feedback value for the position
controller via parameter
60.01 POS ACT SEL . In addition, at least one latch signal
must be available in the revolution to correct the actual position of the drive.