High voltage PSU input to low DC out experience?

[Estelles]

Hi

I'm working on a design for a power supply that feeds from a off grid generator and can output up to 700VDC. Has someone got experience on steping this down to 12VDC and about 2 Amps?

I have been looking a switch mode psu but all need a high frequency transformer (don't know where to find the right one). I would like to keep it simple as the unit doesn't have to be isolated.

I was also thiking using the DC and chop it at 50Hz but it is not easy to find transformers that can take 700 Volts, my only option probably would be to use two 240 VAc windings in series. Does it make sense?

Of course, as a last resort I could use a standard PSU in DC mode and stop the PSU at 350VDC with a MOSFET or IGBT working as a switch but not sure if this is the best solution.

Any ideas on this? I'm really confuse and not sure which direction to take so any suggestion will be very welcome. :?:

Ed

 

[btbass]

I use an FSD210 buck regulator (Fairchild) to switch 450 volts to 12V, 120mA non isolated. The chip is rated to 600Volts. Maybe Fairchild or other ic maker has a buck regulator that could do the job?

 

[Estelles]

Thanks a lot!

that seems a good option (above all Fig2 on the datasheet).
Where do you get the hi frequency transformers from? and best of all, how do you know which one is best for it?

The FSD200 works up to 700 volts which is perfect, but power is a bit low so I would need to use a bigger MOSFET/IGBT to get the current I need. I suppose I could find an application note for that.

Would you recommend any place to buy the high frequency transformers? Which criteria do you use to select it?

Thanks

Ed

 

[saeidshirvani]

Hi

I'm working on a design for a power supply that feeds from a off grid generator and can output up to 700VDC. Has someone got experience on steping this down to 12VDC and about 2 Amps?

I have been looking a switch mode psu but all need a high frequency transformer (don't know where to find the right one). I would like to keep it simple as the unit doesn't have to be isolated.

I was also thiking using the DC and chop it at 50Hz but it is not easy to find transformers that can take 700 Volts, my only option probably would be to use two 240 VAc windings in series. Does it make sense?

Of course, as a last resort I could use a standard PSU in DC mode and stop the PSU at 350VDC with a MOSFET or IGBT working as a switch but not sure if this is the best solution.

Any ideas on this? I'm really confuse and not sure which direction to take so any suggestion will be very welcome. :?:

Ed

 

[Estelles]

HI

I think you forgot your reply.

Cheers

 

[btbass]

As the circuit is not isolated, I dont need a transformer. I use the application circuit in the data sheet.

 

[Estelles]

Thanks!!

What is the maximum current you are able to get? The specs mention max 300mA.
I don't seem to get more than 200mA @ 12Vdc.

It seems to be other device FSB211 or FSB201 which can provide nearly double the power.

By the way, this is the design I'm using: