Hi Arunkumar,

I'd recommend designing your controller so you can get a phase margin between 50 to 60 degrees for the compensated system.

For the starting time, usually "soft start" is used (i.e. duty cycle is gradually increased by the controller. If you are using a dedicated IC chip for controlling your boost converter, it should have a soft starting capability. Look for "soft starting" pin in the datasheet.)

Also, some overshoot/undershoot on the output voltage during perturbations is unavoidable and usually acceptable,if they are confined within a percent of output voltage (6-10% that you see for your converter, seems typical values for such perturbations.)

i agree with Ali Shahabi, nonlinear would cost you in hardware as well design complexities., if you are lokking for industrial solution.

Taimur Zaman ,Ali Shahabi ,Mohamed Azab

Thank you all..

I heard about the right hand zero will give a boost for the boost converter output at the starting time. Is it possible to eliminate using PI controller?

Hi Arunkumar,

I attached an app note that talks about the right-hand zero of the boost converter (refer to the discussions starting at the bottom of page 5). To deal with the right-hand zero, it says:

"The usual method to deal with the RHP zero is literally "pushing it out" to higher frequencies where it can't significantly affect the overall loop. Equivalently, we need to reduce the bandwidth of the open-loop gain plot to a frequency low enough that it just doesn't "see" this zero. In other words, the crossover frequency must be set much lower than the location of the RHP zero. In effect, the bandwidth and loop response suffers on account of the RHP zero."