600v to 12v powersupply design

[francis29]

I want to design a powersupply that takes 600V DC as input and deliver 12V DC / 1Ampere as output.
what topology should i follow to make this happen.

 

[Easy peasy]

2 switch flyback... resonant

 

[Naseer Ahmed]

Dear convert this DC to Ac first... The only possible way...

 

[francis29]

Can you explain a bit more.
i have dealt with single switch flyback which is pretty easy.

 

[Naseer Ahmed]

I can't understand you scheme of flyback! But as you know what happen in Uninterrupted Power Supplies (UPS).

You will use a 555 timer, a centered tap transformer 660 / 12V, two BJTs, a rectifier and a filter (It will be an expensive adn time taking process though).

 

[Easy peasy]

there are plenty of references on the web for 2 switch flybacks to do this...

 

[treez]

i recomend the highly secret, but actually easy, "cascaded buck using sic mosfets"
It just uses one controller, but two high side fets, with an intermediary rail. You have a high side CST current sense at the upstream fet.
There is other posts on this forum about it...i will link them here for you, let me go and seek them..

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here is it..
https://www.edaboard.com/threads/347894/

..but then again, with just one stage (not cascading) your duty cycle will be 12/600....which is very low, so you could just use a low enough frequency till you get a decent length on time...big components , but do you care?

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posts #11 and #12 show the schem of the cascaded buck

 

[francis29]

Oh sorry treez.
I forgot to mention. I need isolated power supply.

 

[treez]

ok, just put a flyback on the output, or do a flyback from the start, its only 12w.

 

[brushhead]

Single switch flyback would be easiest solution. I have done something like this but it was a 250W power supply.

 

[francis29]

okey. but how can i give gate signal to the switch(mosfet)?
Lot of flyback / pwm ICs are available, but Vcc to the ic is much lower than 600V. Usually in the range of 30-60V. So how to power the IC from the same input 600V?

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And one more doubt is i have to design DCM or CCM?
Which one is good for this application?
The total power is only 12 Watts (12V/1A).