Siemens SINAMICS S120 Function Manual page 151

Control direction of the speed control loop
For rotating motors, in encoderless operation with a small positive speed setpoint (e.g. 10
rpm), the actual speed value (r0061) and the speed setpoint (r1438) must have the same
sign.
Before using the pole position identification routine, the control sense of the speed control
loop must be corrected (p0410.0).
For linear motors, see SINAMICS S120 Commissioning Manual.
NOTICE
Inaccuracy when determining the commutation angle
If more than one 1FN3 linear motor is using saturation-based pole position identification for
commutation (p1980 ≤ 4 and p1982 = 1), this can reduce accuracy when the commutation
angle is determined. If a high level of accuracy is essential, (e.g. when p0404.15 = 0 or to
determine the offset of the commutation angle using p1990 = 1), the pole position
identification runs should be carried out consecutively. This can be achieved by staggering
the time at which the individual drives are enabled.
Pole position correction with zero marks
The pole position identification routine provides coarse synchronization. If zero marks exist,
the pole position can be automatically compared with the zero mark position once the zero
mark(s) have been passed (fine synchronization). The zero mark position must be either
mechanically or electrically (p0431) calibrated. If the encoder system permits this, then we
recommend fine synchronization (p0404.15 = 1). This is because it avoids measurement
spread and allows the determined pole position to be additionally checked.
Suitable zero marks
● One zero mark in the complete traversing range
● Equidistant zero marks
● Distance-coded zero marks
Selecting the reference mark for fine synchronization for determining the pole position using zero
marks
A precondition for determining the pole position using zero marks is that the zero mark
distance of the encoder is a multiple integer of the pole pitch / pole pair width of the motor.
For example, for linear motors with measuring systems where this is not available, the drive
permits the zero mark which is used for the reference point approach, to be used for fine
synchronization. With this zero mark, due to the mechanical arrangement, the commutation
angle = 0 or is available as offset in p0431.
Drive functions
Function Manual, (FH1), 04/2014, 6SL3097-4AB00-0BP4
WARNING
Servo control
4.14 Pole position identification
151