Compensation suggestion for rhpz compensation

[dip_10]

Compensation suggestion

Hi all,
I am designing a dc-dc converter which has a rhp zero. the transfer function is of the form K(1-a1s])/(1+bs+cs²). When I tried bode plot with Matlab, the gain plot is OK, but I dont know why matlab starts bode plot from 360° and then goes on reducing phases. I know this is equivalent to sarting from 0° and then going negative, which should be the correct plot.
So, I am a bit confused. Can someone please help...
Also can someone please suggest me a proper compenstion scheme. This is the first time I am designing a practical coneverter. So, please help me out.
Thank you.
Deep.

 

[mathsolvesit]

Since this is your first design, it may be most practical to set the zero crossover of your loop way below the RHPZ frequency. By doing that, at the frequency at which that RHPZ starts raising the gain, your total loop gain will be far below 0dB and the system will be stable.