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# why PI compensator in Boost Feedback Control

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#### mengghee

##### Full Member level 3
pi compensator

I am just wondering why do we need a pi compensator in boost control scheme. In Voltage control mode ? thank you.

#### hoonsk

##### Member level 2
boost feedback control

Typically PI is not enough in Boost DC/DC. Perhaps unless you set the dominant pole way inside (close to DC), and have a small bandwidth. The power train pole and right half plane zero are just too difficult to handle since they are functions of Vout/Vin, L & C, which means the compensation can be difficult to be cancelled off.

### mengghee

Points: 2

#### mengghee

##### Full Member level 3
compensator for boost

Typically PI is not enough in Boost DC/DC. Perhaps unless you set the dominant pole way inside (close to DC), and have a small bandwidth. The power train pole and right half plane zero are just too difficult to handle since they are functions of Vout/Vin, L & C, which means the compensation can be difficult to be cancelled off.
hoonsk,

forgive my newbieness... haha but what is the dominant pole ? and what bandwidth ? power train pole and right half plane zero ? i am very poor in control system.

regards,
mengghee

#### hoonsk

##### Member level 2
Dominant pole is the pole you have (or set) at the lowest frequency. You want to design it to have good phase margin. I think it would be good if you can refer to some info from textbook...as my explanations are not (obviously) as good as theirs. I recommend "Fundamentals of Power Electronics" by Erickson, the book says everything I mentioned, plus much more, and with great diagrams to illustrate the points.

mengghee said:
Typically PI is not enough in Boost DC/DC. Perhaps unless you set the dominant pole way inside (close to DC), and have a small bandwidth. The power train pole and right half plane zero are just too difficult to handle since they are functions of Vout/Vin, L & C, which means the compensation can be difficult to be cancelled off.
hoonsk,

forgive my newbieness... haha but what is the dominant pole ? and what bandwidth ? power train pole and right half plane zero ? i am very poor in control system.

regards,
mengghee

Points: 2