Siemens SINAMICS S120 Function Manual page 590

Function modules
9.15 Cogging torque compensation
Example 1: steady, supplementary learning for linear motors
The entire traversing distance cannot be measured for linear motors in a single operation. A
learning process can only be initiated once a linear motor has been brought up to speed. We
therefore recommend that the traversing distance be measured over several steps.
Procedure
To measure the traversing distance of a linear motor, proceed as follows:
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. Check the table indexes calculated from r5254[2] (start value) and r5254[3] (end value) only
after the end of this first learning process.
– If the start value is higher than the final value, the values are learned from the start value
– If the start value is less than the final value, then the values are learned from the start
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 path overlaps the previously performed 1st
learning path 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, end 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.
Example 2: Filling process depending on the direction of motion
Compensation depending on the direction of motion is beneficial when the operating point
changes depending on the direction of motion given large friction forces.
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up to the end of the table and from 0 up to the final value.
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.
Function Manual, 06/2019, 6SL3097-5AB00-0BP2
Drive functions