problem about wide input voltage

[chenboshi]

Hi,I have a problem about a DC/DC converter,which need a wide input voltage,nonisolated:input 19~150V,output 19~30V.So the boost and the buck converters are employed in series.Now the problem is:How can I improve the efficiency?And in such wide input voltage,how can I ensure the stability of the converter?
Thank you for your reply!!!

 

[eem2am]

y not just use flyback

good gain and phase marjin = good stability

 

[chenboshi]

Because i didn't need to use a isolated converter,and i want to make the converter simple without a transformer.However the input voltage is too wide,which cause the efficiency of the converter too poor.

 

[dipnirvana]

flyback will better perform in this case

 

[chenboshi]

Yes,it is better to use the flyback in this case,and there are so many converters using the flyback.
However,i was told to use the converter which is non-isolated.And that is the problem .

Added after 1 hours 22 minutes:

And the power of the converter is 500W,which is not suited for the flyback.

 

[chenboshi]

Is there some topologies that suited for this case?

 

[vishnu143_chennuri]

hi can i kow whats the title of your project ...............

 

[Orson Cart]

This is not a trivial design, a flyback could be made to work with multiple o/p windings, each rectified then paralleled. Interleaved layers of pri/sec to get the leakage down to keep the efficiency high, else a Cuk or Sepic or a buck converter that can sustain 100% duty cycle on the main switch.
Regards, Orson Cart.