Lenghth vs Speed control for Drives

[Racer5039]

I agree. It was a Q & dirty way of getting the job done but I was given a budget that would not cover any other way. In this case it was a life cycle test of a product, over 1,000,000 cycles. When the test started it would run 24/7 to the end. run out 6 ft stop retract 6 ft. turning a crank handle like a hand wench. It would hold +/- of less than .200" over all travel, all day, all night. I was just giving something that worked for me. Use at your own risk.

 

[Peter Nachtwey]

The bigger issue here has already been pointed out. You are trying to do position control with a velocity device. Square peg in a round hole.

Hydraulic systems are velocity devices. Motors are basically acceleration devices if you consider the torque, angular acceleration, is roughly proportional to current.

This is a textbook positioning application. CAN you do it with a VFD?...perhaps...can you do it the same way, all day everyday with a VFD, and get the app tuned up and running in less time than a non-VFD? probably not.

The problem is the lack of motion controller.
In cases like this we prefer the VFD acceleration and deceleration ramps be disabled and that the internal VFD velocity loop be tuned well. Now our motion controller can provide voltage signals proportional to the desired velocity.