Hello, need some help with a 753. I am trying to find a setting in the drive that will smooth out the speed control. Right now the drive is constantly going from Accel to Decel to At speed, trying to keep the set point. Is there a setting to smooth this out a little bit?
PowerFlex 753
- Thread starter grider75
- Start date
widelto
Member
Maybe your accel and decel times are too short.
GTUnit
Member
The drive will respond to whatever speed it is commanded to match.
If the speed command keeps changing then the drive speed will keep changing as you observe.
Where is the speed Ref value coming from? PID?
If the speed command keeps changing then the drive speed will keep changing as you observe.
Where is the speed Ref value coming from? PID?
kamenges
Member
I agree with GTUnit. I have drives that never settle at speed for any real period of time. If you don't like seeing the displays flop around you may be able to change the size of the at speed window. But it won't really affect how the drive is operating.
Keith
Keith
jraef
Member
What you are describing is called "hunting" and that's exactly what a PI or PID loop is for. Are you using that? If not, there's the answer.
Grider, what kind of setup do you have? Is your setpoint the commanded Hz on the VFD? or analog reference? Are you using feedback, (0-10V, 4-20mA)? From what, encoder, tach, vfd calculated? Is your load demand variable? What is the range of speeds you're trying achieve?
Be sure your feedback is clean and consistent. Be sure you give your motor time to respond. If using a PID, start slow and detuned.
Be sure your feedback is clean and consistent. Be sure you give your motor time to respond. If using a PID, start slow and detuned.
kekrahulik
Member
rkukl nailed it for you.
Alternatively, per his attachment, you can set Speed Reg BW to zero and then tune the Kp and Ki yourself. There are some applications that it is necessary to tune it yourself. I certainly recommend that you first try increasing Speed Reg BW first to see if that gets you the stability and response that you need.
Alternatively, per his attachment, you can set Speed Reg BW to zero and then tune the Kp and Ki yourself. There are some applications that it is necessary to tune it yourself. I certainly recommend that you first try increasing Speed Reg BW first to see if that gets you the stability and response that you need.
spence144db
Member
I don't know..I would trend the ref frequency. Sounds like the drive is just doing what it was told to do. Is this part of a control logix platform? do these same symptoms show themselves when you set the drive up with CCW and performed static, rotate, and inertia tunes??
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