PowerFlex 525 - How to begin setting up for a Open Loop Vector Control application

[Baker in Virginia]

Good Afternoon ,

I am getting ready to refurbish 2 machines . It will have 3 SEW gearmotors on each machine. I would like to keep the selected speed very consistant with what speed is selected. I was going to use encoders , but to reduce cost , I was thinking of going with the option that was discussed on an earlier thread , Open Loop Vector Control. What I would like to do is have the operator select recipes of products they run . In these recipes , will be the speed that these 3 motors run in RPM. In the Compactlogix I will figure out what speed the motors will run according to the RPM setting.

My question is , other than using encoders , what is the best way to keep a constant speed on these motors. I imagine there is alot of factors that cause a motor to slow down and speed up , correct ? If I would go with the Open Loop Vector Control , how would I start setting that up. I imagine Autotuning would be a start , correct ? I tried to find some technotes , but really only found brochures concening the PowerFlex 525 and it's options.

Would you folks have any infornation that will point me in the right direction. Also , if you believe I am approaching this the wrong way , let me know.

Thanks so much in advance.

 

[jraef]

To get the most accurate speed control without adding an encoder, use the rotating autotune. So you go to parameter P040 and and set it to "2" for "Static + rotating autotune" and give it a Run command. It will perform the static tune first, then follow it up with a rotating tune. So make sure it is safe to run the machine at full speed and if not, uncouple the load from the motor.

Semantics note: there is no "Open Loop Vector Control" in a PF525, only Sensorless Vector Control (SVC) or Flux Vector Control (FVC), with an encoder. SVC will give you speed accuracy of up to 0.5%, Flux Vector Control with an encoder will get you 0.1% accuracy.

There is a difference between SVC and Open Loop Flux Vector Control, which is only available in the PF750 series. Open Loop FVC with a PF750 can be 0.001% accurate, so it's a matter of how accurate you need it to be.

 

[Baker in Virginia]

Thanks Sir ,

That is good information. I think 0.5% will be plenty close for our application.