Determining The Angular Commutation Offset - Siemens SINAMICS S120 Commissioning Manual

2.13.6

Determining the angular commutation offset

When the system is commissioned for the first time before adjusting the angular
commutation offset, it is possible that the drive could be completely incorrectly
commutated. Current is fed into the motor at the incorrect time for an incorrectly
commutated motor. As a consequence, it can make unintentional movements, for example
it can rotate at a high speed in the incorrect direction.
As a consequence, for safety reasons you must limit the current to 20% of the maximum
motor current using parameter p0640.
You can determine the pole position, required for synchronous motors, for the SIMOTICS T-
1FW6 built-in torque motors using a software-based automatic pole position identification
technique.
The following two techniques are suitable for all frame sizes of SIMOTICS T-1FW6 built-in
torque motors:
● The motion-based technique p1980 = 10
● The saturation-based technique (1st harmonic) p1980 = 1
Also refer to the information in Chapter General information for setting the commutation
(Page 172).
Parameter entries / commutation setting
Incremental measuring system
Set the drive enable signals (OFF3, OFF2, OFF1). This results in coarse synchronization. A
successful coarse synchronization is indicated by the parameter r1992.9. Then select the
automatic determination of the angular commutation offset using p1990 = 1. Alarm A07971
is output while the angular commutation offset is being determined. You must then move the
drive over the zero mark. When the zero mark is passed, the angular commutation offset is
entered into p0431. p1990 is automatically set to 0 after the angular commutation offset has
been determined. Alarm A07965 is displayed as a prompt to save the change in a non-
volatile fashion.
Absolute measuring system
Set p1990 = 1 before activating the enable signals. By activating the enable signals, the
angular commutation offset is entered into p0431 and p1990 is automatically set to 0. Alarm
A07965 is displayed as a prompt to save the change in a non-volatile fashion.
Commissioning Manual
Commissioning Manual, (IH1), 01/2013, 6SL3097-4AF00-0BP3
CAUTION
2.13 Commissioning SIMOTICS 1FW6 built-in torque motors
Commissioning
193