Phase shift half bridge converter?

[cupoftea]

Hi,
We've all heard of the PSFB....what about its cousin, the PSHB?

Simply replace two leg fets with caps (split caps)....leave the big leakage inductance in the primary side, short out the output inductor, and there you go.
Ive seen this supply quite a few times...but no documentation on it.
It gets switched at max duty cycle all the time.......in burst mode when light load.
Whats its problems?....i would imagine reverse recovery like PSFB?

 

[FvM]

PSFB - involves phase shift between legs.
PSHB - Where's the phaseshift?

 

[cupoftea]

Thanks, yes i agree, but it just operates at max duty cycle all the time...no phase shift

 

[BradtheRad]

The two-cap stack divides supply voltage in half. Thus a transformer needs twice as much step-up ratio.

The advantage is simplified switching.

 

[cupoftea]

Thanks, also, i forgot to say, because its half bridge, you cant have any current limiting in there...otherwise the rail splitting caps will go unbalanced.....so you just basically do on/off control till your vout gets to where you want. Also, best to use IGBTs as they can handle the huge overcurrents you get when you have no current limiting.
Have you seen offline 240VAC PSU's like this?