Hello everyone,
I'm currently working on a project that requires me to control a Siemens Sinamics V20 frequency inverter (which controls a pump) and a flow control valve to regulate the volume flow throughout our test bench. The setpoint for the volume flow is set using a numeric control, and we measure the volume flow rate right before the pump. Once the RPM of the motor becomes too low, the water flow through our system becomes irregular because the pump can no longer support the low volume flow rates (the water needs to travel vertically for about 1.3 meters right after the pump).
This is when the control valve (located on the vertical pipe after the pump) comes into play. It narrows the opening of the pipe, creating "resistance" for the motor, allowing the water to flow again at a smooth rate. With this valve, we can achieve flow rates far lower than the pump’s limit.
To summarize: the pump regulates the volume flow from maximum to minimum flow rates. Once we go lower than the minimum (via our numeric control), the flow control valve should automatically start to engage and reduce the internal opening to achieve the desired volume flow rate, which the motor can’t achieve on its own.
I am tasked with programming this regulation within LabVIEW, and I’m unsure of how to proceed. I will most likely be working with case structures and probably a PID controller. However, my professor has also suggested that, instead of using a PID controller, we could use tabular values because it's "the better alternative" (tabular values basically mean that, for example, if we set 0.4^3 m/s, then the valve should close by, let’s say, 9%, which is based on a whole list of possible outcomes).I genuinely have no idea how I’d do that, as PID seems much simpler, but I'm not sure.
I have attached an image of our test bench for better clarification.
(tank on the right, flow sensor on the left next to it, pump + ASM on the left, and flow control valve (blue thing) on the top left).
I hope I have made my problem somewhat clear, if not just comment and I'll repsond right away!
I really appreciate any and all help. Thank you!