08-23-2024 05:13 AM
I modified the code, and it works but I need to determine the gains because I just assumed them
08-23-2024 05:44 AM - edited 08-23-2024 05:45 AM
Hi alhabeeb,
@alhabeeb wrote:
I modified the code, and it works
It looks much better now.
You should add a small wait inside the loop and limit the output range of the PID.
@alhabeeb wrote:
I need to determine the gains because I just assumed them
Yes. See my comment on step responses above...
You could also try to determine PID gains from analyzing your system:
After all it's a "simple" physical system! 😉
08-23-2024 05:50 AM
@GerdW a écrit :
Hi alhabeeb,
@alhabeeb wrote:
I modified the code, and it works
It looks much better now.
You should add a small wait inside the loop and limit the output range of the PID.
@alhabeeb wrote:
I need to determine the gains because I just assumed them
Yes. See my comment on step responses above...
You could also try to determine PID gains from analyzing your system:
- heat capacity and massflow of the hot fluid
- heat exchange rate and (thermal) delays in the cooler
- input temperature and (max) massflow of tap water
- …
After all it's a "simple" physical system! 😉
Should I use case structure to add limits to PID?
08-23-2024 05:54 AM
Hi alhabeeb,
@alhabeeb wrote:
Should I use case structure to add limits to PID?
No, you should read the LabVIEW help for the PID function…
08-23-2024 06:04 AM
08-26-2024 02:48 AM - edited 08-26-2024 03:09 AM
@GerdW a écrit :
To determine the PID gains you can do some step-response tests and apply the common rules on the step response measurements.
Thanks for all your support. I'm new to use Labview, and I know a little about the control. Would you give me more details about how to determine the gains?
Thanks
Baqer
08-26-2024 03:21 AM
Hi alhabeeb,
@alhabeeb wrote:
Would you give me more details about how to determine the gains?
Have you tried to search for manuals (using your favorite web search) on your own? "Searching for relevant information" is basic knowledge for engineers!
I found this article easily…
08-26-2024 04:01 AM
I used this, and it worked with my system.
08-26-2024 04:06 AM
Hi alhabeeb,
@alhabeeb wrote:
I used this, and it worked with my system.
So you implemented a plain P-controller!?
This is (in my experience) VERY unusual for a thermodynamic system, involving heat exchangers with massflow-dependent properties!
08-26-2024 04:14 AM - edited 08-26-2024 04:50 AM
Hi,
Right now my test bench is not completed, so I just attached a thermocouple on the tap water pipe to represents the (T_f_out) and run the VI. When the T_f_out greter than the setpoint the valve opens and when it is lower the valve close. If the T_f_out high greter than the setpoint, the valve is full open.