VFD Speed Setpont via PID loop problem

TimD

Lifetime Supporting Member
Join Date
Aug 2007
Location
New Hampshire
Posts
235
Hi, I have AB PowerFlex 400 drives set up on DeviceNet. I use MOV blocks to sent an int value of 0-60 to my drive and the drive happily responds, etc.

Now I set up a PID loop. I have covered all the bases (AI scaling, setup) and in AUTO, the loop responds the way I want it to, by moving the drive speed up/down in proportion to SP.

Only problem is, my drive does not react.

The output of the PID block sends 0-16733 and I am using two (I am sending information to two drives in 'sync') so I put two SCP blocks and scaled my out to 30-60hz. the out of the scaling block writes to O:4.5 and O:4.9 just like my old MOV code did.

The drives start at 30Hz and stay there, even though the out of the scaling block is writing 50 or so Hz to the drive input.

Anyone have any suggestions? Please and Thanks.

tim
 

Similar Topics

Working on 2 VFDs for two motors, they follow any speed command when local and in hand. Once I try to give a Speed reference from my PLC they both...
Replies
10
Views
2,118
Hello, So I was asked to turn up the speed on a VFD to allow a carriage to move a little bit faster and avoid getting stuck. Im not sure the exact...
Replies
2
Views
712
I'm trying to figure out how to read the actual speed reference value from the move blocks, writing to a DB that is being sent to the VFD. For...
Replies
5
Views
2,613
I don't understand how vfd detects speed when we are running in open loop control (sensorless). For me only possible way; during auto tuning it...
Replies
4
Views
2,619
Hey PLC.net, I'm working with a PowerFlex 525. It's communicating within the panel via ethernet but I need to send the speed out 4-20mA via the...
Replies
2
Views
1,857
Back
Top Bottom