ac dc conversion question.

[ljy4468]

Hi all
I have some stupid question about ac-dc conversion.

As you already know, diode-bridge is connected to AC line and rectified voltage is go through flyback stage in case of flyback ac-dc smps.

- AC Plug -> Diode bridge -> Flyback stage


Then let me write a stupid question.
How about below construction?

- AC Plug -> transformer (10:1) -> diode bridge -> buck or boost stage.

It is electrically isolated from AC to output.

But I've never seen that configuration. So anyone tell me why that's not used?

Thanks in advance.

 

[FvM]

But I've never seen that configuration. So anyone tell me why that's not used?

I don't agree.

Transformer power supplies with secondary switch-mode converter have been used for decades and are still used. But these days primary switch mode converters ("off-mains" switchers) are preferred due to weight and size savings.

 

[ljy4468]

Thanks for your answer.
Could you please let me know any example of transformer power supplies? (Transformer front-end instead of diode bridge)
I cannot find any url.
Thanks.