ABB ACS850 series, Firmware Manual

Page: 30 / 260

30 Program features
Application macros
See chapter Application macros (page 51 ).
Autophasing
Autophasing is an automatic measurement routine to determine the angular position
of the magnetic flux of a permanent magnet synchronous motor. The motor control
requires the absolute position of the rotor flux in order to control motor torque
accurately.
Autophasing is applicable to permanent magnet synchronous motors in these cases:
One-time measurement of the rotor and encoder position difference when an
absolute encoder or resolver (one pole pair) is used
With open-loop motor control, repetitive measurement of the rotor position at every
start.
Several autophasing modes are available (see parameter 11.07 Autophasing mode ).
The turning mode is recommended especially with case 1 as it is the most robust and
accurate method. In turning mode, the motor shaft is turned back and forward (±360/
polepairs)° in order to determine the rotor position. In case 2 (open-loop control), the
shaft is turned only in one direction and the angle is smaller.
The standstill modes can be used if the motor cannot be turned (for example, when
the load is connected). As the characteristics of motors and loads differ, testing must
be done to find out the most suitable standstill mode.
The drive is also capable of determining the rotor position when started to a running
motor in open-loop or closed-loop modes. In this situation, the setting of
11.07
Autophasing mode has no effect.
ș
Absolute encoder/resolver
Rotor
N
S