PID Tune: Plant cannot be linearized. Why?

Hello everyone,

I'm using simulink for simulating a cooling system. When I try to use the tune button on the PID it opens the tuning window and say:

Plant cannot be linearized.

Why is this happening?

The PID is doing is job. I've attached files.

Thank you very much for the help,

Norman

Answer 1

[Arkadiy Turevskiy]

The plant is linearized, but the linearization at t=0 is a gain of zero. Most likely this happens due to initial conditions in the model. You can ask the PID Tuner to linearize the model at a simulation snapshot of say t/2, when everything comes to steady state.

When you do that, the PID Tuner successfully linearizes the model and designs a PID controller.

Here are the snapshots of the steps using R2014a.

Answer 2

[Norman]

Thank you very much for your answer, I've got what I have to do, but of I push the Re-linearize Closed Loop command, nothing happens.

I'm also working with the R2014a. Thank you for the support,

Norman

[Arkadiy Turevskiy]

Try setting simulation time to 3600 instead of t, as you have now. When I tried your model yesterday, somehow using t instead of a number for specifying simulation time was causing PID Tuner some trouble. This is a bug that will be fixed. Meanwhile, just type in 3600 and everything should work.

[Norman]

Now it works fine! Thank you very much!

Norman

[Adhip Shukla]

Hi Arkadiy,

In my model also it is showing the same error and I tried what you have suggested above can you look into my model once and tell me how to tune my PID block.

[Ayesha Sandamali]

I am designing a grid connected PV system. In that model I am using three PI controllers inorder to control iq, id and output dc voltage of the solar array. Can suggest any methods to tune these controllers.

[mohamed farouk boukli hacene]

@ayesha sandamali i'm working on a pv inverter control too and a pv optimizer so i need exactly what you're asking for, did you find the answer? thank you

[Sharjeel Khan]

@Ayesha Sandamali i'm also simulating and grid connected PV system. I'm also facing the same problem can you help me with that please??