Why my Simulink PID Autotuner have a strange result ?

Hello everyone, I'm new at Matlab and I just design a floating interleaved buck DC converter for battery charger in Simscape. I want to make current controller with current reference 50.14 Amps using PI controller but I'm having trouble tuning it. I used PID Autotuner but I get a strange result in which there is oscillation after 0.035 second as shown in the picture. I have also attached the file above. Any suggestions to this problem ?

Answer 1

[Joel Van Sickel]

The basic PID tuner requires a plant model that it can analyze analytically and linearize if need be. As your system has switches in it, this isn't possible. The traditional approach only works with specific converter topologies that can have an average implementation. Instead, you need to use the frequency domain based workflow. You can get the frequency response of your converter (open loop) and use that to autotune the PID controller. https://www.mathworks.com/help/slcontrol/ug/frequency-response-based-pid-tuner.html