Best diode for a boost converter in hspice

[baltzois]

Hello,
I try to find the best diode for a boost converter and i try in hspice different models of diodes. Why the output voltage decreases when i change the diode if the forward voltage drop of all the diodes is for about 0.7v?? Even when i use a schottky diode that has less losses from a normal one the voltage output decreases...Sorry but i am a starter in power electronics.

Thank you in advance

 

[dick_freebird]

boost converter diode

Reverse recovery time will "suck back" a slug of charge
on every cycle, that is a switching loss. There is only so
much energy to be delivered from the inductor and it should
all go forward, but never entirely does.

Diodes' series resistance is a conduction loss, including
but not limited to the rated Vf. Schottkies have a lower Vf
but often poorer series resistance.

If the diode's capacitance makes crazy ringing, that can also
cost you extra. Below-ground ring cycles tend to be a total loss.

It may be more helpful to think in terms of inefficiency,
tabulate the various loss elements and work from that.

 

[baltzois]

Re: boost converter diode

Thank you for your reply!
But is it normal to have different output for about 10V between two simulations of the same boost converter with just changing the diode??
The simulations are held in hspice..