PID Flow Rate Control

Hi,

I am new to PID control, wondering if anyone can help me with this. We have a flow meter goes into VHSC point io card as input, analog output goes out to VFD control the pump. I have the pump, flow meter and material information. My question is how can I find the right value for proportional gain and integral gain.

Thank you!

The quick&dirty way is to first leave the I part at zero, gradually increase P until the system behavior becomes instable, in the sense that it does not keep moving towards the setpoint anymore but rather oscillates around it. Then back down a bit until it becomes stable again. From there gradually increase the I part until you are happy with the response. Too much I makes the system unstable again.

Works for setpoints that are relatively stable. Widely varying setpoints may see some overshoot: initial oscillation around the new setpoint if the system reaction time is slow which is often the case.

Please note this is the Q&D approach. Better results may be obtained with a better understanding of both the time behavior of the process at hand as well as some of the math involved. If you want to delve deeper there is plenty of information to be found on the internet as well as in books.

thank you for your replies!