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Current Loop Tuning Issue


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I was hoping you could shed some light on an issue that we have encountered.


Upon performing manual current loop tuning, when the current has reached steady state I am noticing cyclic dips in the current (which the integrator responds to). I have attached a picture




We are using an ACC-5E3 card with Geo MACRO Drives


I have checked all of the commutation and direct PWM setting along with the pointers to the Geo MACRO registers.


Do you have any suggestions?

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What is the inductance of your motor? Do you have a ferrite core on the motor leads? That might help.

Ph-Ph = 18.5mH, exact same setup used in production and same issue does not exist



What are your current loop gains (Motor[x].IiGain, Motor[x].IpbGain, Motor[x].IpfGain)?

Motor[x].IiGain = 0.152

Motor[x].IpbGain = 0

Motor[x].IpfGain = 2.3


What is the value of Sys.PhaseCycleExt?

It is set to 1



What are your clock settings on the Power PMAC and on the Slave (Geo MACRO)?

Standard settings




MACRO MI992 == 3275 (18.004khz)

MACRO MI997 (Phase Clock Freq Control) = 0


We are checking our power supplies to the unit later on.

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Hello Steve,


I have a few concerns:


1. I have set the ADC offsets already.


2. My main concern is that if you physically hold the output shaft of the motor, when it is holding a constant position target you can feel the vibrations in the motor shaft, which in a high precision position application is not be acceptable


3. This issue is not present on our other PMAC which uses the same setup.


Thank you

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  • 6 months later...



So I have encountered another current tuning issue on the same development setup and I have no idea why this started.


For some reason my PPMAC reset to default values and now the current control for my motors is doing the following. Has anyone ever encountered this


I have checked all the previous setting and both GEO MACRO and PPMAC have the same PhaseFrequency



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