Siemens SINAMICS G120X - Common Issues and Possible Solutions; Speed Controller Optimization

3 Commissioning using IOP-2
G120X commissioning guide for permanent magnet motors PMSM
Entry-ID: 109780815, V1.0, 07/2020
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© Siemens AG
2020 All rights reserved
NOTE
If fault 7969 Drv: PolID incorrect appears try the remedy detailed in the Operating instruction
manual in chapter: Warnings, faults and system messages.
If the problem persists, try changing the PolID method in p1980. Possible values for PMSM
motors are 1, 4 or 10. Value 4 is most suitable for IPM motors. Value 10 can be used only
when the application allows for motor shaft to freely move before start (i.e. ventilators,
centrifugal pumps etc.).
When you later re-run Motor identification test the value in p1980 will be automatically
reset to 1. You must change it manually to the desired value and perform Save RAM to
ROM afterwards.
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Increase the speed to maximum and check the current at worst case load (usually open
valve/flap in system). The drawn motor current shouldn’t be greater than rated motor
current even if it runs for a longer time.
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Stop the drive and save parameters by
going into the Extras menu, selecting
"Parameters settings" and finally "Save
RAM to ROM".
3.3 Common issues and possible solutions
3.3.1 Speed controller optimization
In order to avoid issues with drive stability or speed overshoots it is recommended to perform an
automatic speed controller optimization. To do it you will need to know motor and load moments
of inertia. If you don’t know them exactly you can make a good estimation by using known data
of similar motor/load of the same rating.
Update parameters:
p341 – Motor moment of inertia: J
Motor
p342 – Total moment of inertia / Motor moment of inertia: (J
Load
+ J
Motor
) / J
Motor
Then update speed controller gains p340 = 4.
If you still experience speed overshoot increase p342 gradually (not more than in 20% steps)
each time followed with p340 = 4.
Other information including mastering of critical applications can be found in G120X Operating
instructions in chapter: 6.7.3.2 Optimizing the speed controller.