# How can I remove the few peaks before the overshoot, so I only have the overshoot peak and then it directly transition into steady state?

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Samuel Pappalardo
on 25 Feb 2022

Commented: Kevin Rogers
on 1 Mar 2022

I built a buck converter ( circuit will be below):

The parameters are:

Vi = 12V, L = 33e-3, the R next to L =0.5, C = 680e-6 , R next to C= 5e-3, R = 10

This is the output voltage graph i got:

Currently I'm manually tuning the PI to achieve an overshoot of between 10% to 20% and a settling time of 0.01 to 0.1 these are no problem but I just can't remove the oscillations following the overshoot. Also when I change the value of D it mess up the whole graph. Is it possible to remove the oscillations so the overshoot follows directly into the steady state because no matter what I change p and I to it never removes the oscillation before the overshoot and changing d mess up everything

##### 5 Comments

Kevin Rogers
on 1 Mar 2022

wn = 1/sqrt(LC)

2*delta * wn = 1/(RC)

For critical damping delta = 1

Therefor C = 1 / (2*wn * R).

Substitute C inot 1st equation to get L.

### Accepted Answer

Pat Gipper
on 26 Feb 2022

### More Answers (6)

Dr Narayanaswamy P R Iyer
on 25 Feb 2022

Dr Narayanaswamy P R Iyer
on 26 Feb 2022

Dr Narayanaswamy P R Iyer
on 26 Feb 2022

For 8 V output, your duty-ratio should be 2/3 (0.67) for given input voltage.

Zhao Wang
on 26 Feb 2022

Since you have built a Simulink model for the buck converter, you may want to consider tune the PID controller based on the actual model behavior. For a switching buck converter, you will need to conduct frequency response estimation to identify a linear system description at the desired operating point. Using the linear plant model, you can use the PID Tuner App (can be opened from the PID controller block) to tune PID controller gains to achieve the performance you want.

Here is an example about the workflow above: https://www.mathworks.com/help/slcontrol/ug/design-controller-for-power-electronics-model-using-frequency-response-data.html

##### 2 Comments

Zhao Wang
on 26 Feb 2022

Pat Gipper
on 26 Feb 2022

My bad. Change I to 300.

##### 4 Comments

Pat Gipper
on 28 Feb 2022

Antonino Riccobono
on 28 Feb 2022

Dear Samuel,

The difficulties you are encountering are understandable since when you tune a specific gain of your PID controller this will affect the other two. Therefore, manually tuning is not practical.

If you want to learn a systematic tuning workflow so that your feebback performance meets specific dynamic requirements, I invite you to consider the following training course:

Good luck,

Antonino

##### 0 Comments

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