Jittery motion from BLDC motor powered by Copley Xenus plus EtherCAT and run by cRIO 9022 via EtherCAT

[jaredj813]

I have cRIO connected to a Copley power supply via EtherCAT and running in scan mode. When I try to command a smooth sinusoidal motion from the BLDC motor connected to my power supply, I get jittery motion out of my motor. Peak velocity for the commanded sinusoid is well below the velocity limit programmed into the power supply. It appears that the jitters of the system are a result of the 2 ms required run everything.

What really bothers me about this issue, is that when I connect my PC directly to my power supply for motor autophasing and diagnostics, I use a software package supplied by Copley called CME2. Using this software package I can command the same sinusoidal pattern and get very smooth results, even though things are being run from within non deterministic Windows. Might anyone have any ideas on how to fix this issue? I could always drive the power supply with an analog signal, but I'd like to keep all communications over the network setup by EtherCAT.

system specs:

PC: running Windows 7 64-bit and LabVIEW 2013 SP1 f2 (32-bit)

cRIO: 9022 running NI-RIO 13.1, NI-Industrial Communications for EtherCAT 2.7.0, and NI Scan Engine 4.2

power supply: Xenus plus EtherCAT XEL-230-18

[alcava.cr]

Hi there,

I tried to find clues on the manuals (Xenus PlusTM & CME 2 User Guide) but I found nothing really helpful. Something to highlight is the fact that this drive accepts CANopen commands over EtherCAT.

If the vendor software works in windows but you are not able to run it properly in the CompactRIO that means the commands you are sending are not formatted correctly or are not being sent in the appropriate order.

That being said…try to make the application work in LabVIEW (at the windows PC) and after you managed to make it work migrate the application to the 9022. Also, consider contacting the vendor for more specific low level information regarding the communication.

Regards,

[Highland_Controls]

Not familiar with that specific setup, but other drives that receive a position profile via comms have an interpolation setting to smooth the motion between position command changes.