Half Bridge vs Full Bridge

Hello,

I am somewhat new at smps. I am designing a simple circuit to amplify
square wave 400hz signal to 340Vpp signal. Am I correct to assume that
half bridge drive circuit is for single rail only (ie positive swing) an
that what i should use is a full bridge driving 4 MOSFETs?

Also I breadboarded a half-bridge circuit driving 2 MOSFETs. The rai
voltage is rectified line from a variac so that i can ramp it up slowly.
The output signal looks good until I reach about 80V. The the signa
appears to saturate and its amplitude stays at about 60V and will no
increase even with increasing rail voltage.

Thanks in advance.

Paul

 

toyo22r wrote...

Obviously you're doing something wrong, but with so little
detail in your post we can't give much useful advice.

 

A half bridge only fluxes the transformer in 1 direction and so uses
less than it could. Your problem is probably that your bridge
capacitors are not big enough and it would most likely to be cheaper to
use a full bridge which drives the transformer in both directions than
get large capacitors.