Hello Yojan,
I understand that you are trying to remove the high frequency ripple in the output by tuning the PI controller.
Firstly, make sure that the error signal passed into the controller is calculated as the difference between the desired and obtained output signals. This will ensure that the controller will work as intended. Once all the connections are verified the following can be done to reduce the frequency ripple component in the output:
- Decrease the value of proportional term (P or Kp): This can reduce the ripples but will make the controller less sensitive.
- Decrease the value of integral term (I or Ki): This can reduce the ripples but can also increase the steady state error.
- Adding a derivative term and making the controller as PID with a suitable derivative term (D or Kd): This can also decrease the ripples as the derivative term of the PID controller helps in removing the oscillatory part of the output and helps in reaching steady state faster, but this also has some adverse effects.
You can use the inbuilt tuning option that Simulink provides for PID controller block. To do this double click on the PID block to open “Block Parameters” dialog and in this click on the “Tune” button in “Automated Tuning” Section. This opens the PID tuner app where the response time and transient behaviour can be set to suitable values to get the desired response. Clicking on the “Update Block” button writes the tuned parameters into the PID block in the Simulink model. You can read the following documentation to get more information:
You can also use the “Anti-Windup” property from the “Saturation” tab in “Block Parameters” dialog of PID block. The following link gives more information about the same:
