Siemens SINAMICS S120, Function Manual

Page: 632 / 1094

Function modules
8.15 Cogging torque compensation
Drive functions
632
Function Manual, 11/2017, 6SL3097-4AB00-0BP5
8.15.4 Examples
Slow supplementary Learning in a linear motor
For linear motors you cannot measure the complete traversing distance in one operation.
The motor must first be accelerated up to its learning velocity and then learning is activated.
For this reason, it is advisable to measure the traversing distance in several steps.
1.
After the motor has reached the desired speed, (re)activate the slow learning with
p5251.0 = 1.
2. End the slow learning after you have traveled from the right third to the left edge of the
traversing distance with p5251.0 = 0.
The compensation table is now partly filled with values.
3. At the end of this 1st learning, check the table indices determined from r5254[2] (start
value) and r5254[3] (final value).
–
If the start value is higher than the final value, the values are learned from the start
value up to the end of the table and from 0 up to the final value.
– If the start value is less than the final value, then the values are learned from the start
value up to the final value. This also applies if the table progress when learning is
negative. In this particular case, the start value and final value are interchanged after
learning.
4. A further learning process is required for the missing part of the compensation table. In
this example, measure in the opposite direction from the left third of the traversing
distance to the right edge. Ensure that the 2nd learning run overlaps with the 1st learning
run previously conducted, otherwise the measurement will be rejected.
Start the supplementary learning after the desired speed is reached with p5251.1 = 1.
5. After the end of the 2nd learning run, exit the supplementary learning with p5251.1 = 0.
The newly calculated values in the compensation table are brought on to the same level.
Overlapping ranges are averaged, the non-overlapping ranges supplemented and the
mean value removed.
6. If the linear motor has reached the stop, large torques are stored in the table.
In this case, delete the high torques and from the edge and then remove the mean values
with p5251.2 = 1.
7. Activate the cogging torque compensation with p5250.0 = 1 if this has not already been
done.
The cogging torque compensation is then performed with the values from p5260.
8. So that the values in the compensation table are permanently stored, perform a RAM to
ROM.
If they are not saved, the values in the compensation table need to be recalculated after
each POWER ON.