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Power-User

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ATV 930

10/06/2021 5:07 AM

Hello,

In the past we used a single Altivar 71 to control 4 motors on a gantry crane. We used this in the open loop V/Hz function . A laser distance meter with PID control was used to automatically drive this crane into the correct position. Now we are using an ATV 930 drive, which only has vector control. It looks as though the ATV and laser are fighting each other to correct the AI into the drive to obtain the correct speed whenever there is a sudden load change. Is there a way to allow the ATV930 to work similar to v/Hz mode?

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#2

Re: ATV 930

10/06/2021 9:28 AM

Perhaps the <...we...> needs to discuss the problem with the crane manufacturer. That's what the telephone is for.

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#3

Re: ATV 930

10/06/2021 12:42 PM
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#4
In reply to #3

Re: ATV 930

10/06/2021 3:56 PM
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#5

Re: ATV 930

10/07/2021 12:33 PM

This is not an unusual problem, where mechanical conditions will upset the typical vector control parameters programmed into a VFD. Bad coupling, sticky or bent shaft, any unusual torque/speed curve can make vector control unstable. A 4 motor drive seems to be ripe for this sort of non-linear torque behavior.

You could try tuning the vector control loop to be really sluggish, which I have tried and abandoned really quickly, but the best solution is to revert to really stable V/Hz operation, as you figured out for the original install.

Your drive does have the V/Hz operation, it should show up as Custom V/Hz operation and an option on Regulator. You can’t see it because you need to enable the next layer of configuration parameters they keep hidden to prevent confusion for the typical user.

I’ve used Altivar drives, they have the same basic configuration options as all VFDs, and I have yet to see a sensorless vector drive that didn’t have V/Hz mode, provided for exactly the reason you are looking for it.

Hopefully the dynamic response is good enough to achieve your control objectives, patience with ramp times up and down will usually solve your control problems.

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