How to tune the PID of MPPT-PID system for a buck converter

Hello,

I am modelling an isolated plant of PV in simulink (r2022b). I want to compare the differences between a normal MPPT regulation and MPPT + PID with a closed loop. In thefollowing photo both methods can be seen.

For the first method I get what I expect, however, the problem I have is that I do not know how to tune the values of the PID, kp, ki and kd. I have tried the try and error method however in the response I get there is an error between Vref and Vpv and it increase with the time. (See the next photo, the first graph is the output of the PID and the second one, in yellow Vpv and in blue Vref.).

Due to that I have tried to get the transfer function of the system, however the function I get is incorrect, and I do not find the error. I have follow the same method that in the attached paper but for a buck instead of a boost (page 5).

If anyone know how can I tune the PID in order to eliminate the error let me know please. I can share the project if it hepls.

Thanks in advance.

Answer 1

[Aishwarya]

Hi Gorka,

As per my understanding you are facing difficulty in tuning the Kp, Ki, and Kd parameters of the “PID Controller” block while modelling a MPPT + PID Controller for a Buck Converter in Simulink.

Here are few ways that can help in tuning the PID Controller:

• Use “PID Tuner” to automatically tune the “PID Controller” block in Simulink.
• Use methods available in literature to tune the “PID Controller” parameters, one such method is Ziegler-Nichols Tuning method.

Please refer to the following documentation to know more about the functions used:

• “PID Tuner”: https://www.mathworks.com/help/slcontrol/gs/automated-tuning-of-simulink-pid-controller-block.html
• “PID Controller” block: https://www.mathworks.com/help/simulink/slref/pidcontroller.html

I hope this helps!

Best Regards,

Aishwarya