Am designing a battery charger and need some help. these are it's specs:
-should be non-isolated ,
-output current -10 A
-using buck topology
-capable of stepping down mains AC power to about 15 vdc which is fed to a control loop.

i know i need to first rectify 220vac to give around 300vdc. this is then fed into the buck.
now, my first question; can a single buck step down 300v to 15v; or i must use multiple buck converters?
or is there a site i can find similar circuit diagram???

 

You need to use a transformer to step down the voltage to 15V, otherwise your using Thyristor charging with Live mains, highly dangerous.

 

Hello,

As transformerless powersupplies are not allowed here.
See the ToS for more information.
I would suggest to use a transformer as Dodgydave also said.
That way safety is done by isolation of the transformer.

Bertus

 

i agree with you all. i understand all dangers poised with non isolated topology ...... but desparate times calls for desparate measures. have been to all major cities in my country, but i cant get ferrite core transformers.
we still rely on imported electronic goods; but i need a very efficient charger ...not using iron core transformer.
please, refer me to other websites i may seek assistance.....

 

Hello,

You might try the following forums:
ElectronicsPoint
Electro-Tech

Bertus

 

thanks for your replies...
let me try first before i comment further......

 

Hi,

Why not grab an old PC supply and beat it into submission?
Its cheap (or free even), it's got isolation and it's got plenty of power - just need a small change in the feedback.

 

Good point. Search the surplus markets for a 15V, 150 W switching power supply, then put your charger circuit on the output. A big fat stable 15 V source should make the charger much easier to design and control.

ak

 

one solution could be to modify a laptop charger, they usually give out 18v@ 5amp.

 

First, thanks for your replies. I have confirmed that non-isolated power supplies are obsolete. And they are only used in big power supplies. So am forced to go back to the isolated smps.

But picking an old pc switcher or 150w power supply may not suffice. To be honest and straight forward, I intend to charge four 12v/70ah lead acid batteries in series. So I need around: 12v by 4 by 10A equals to 600W. So I felt that non isolated smps would be a cheap and simple solution. But , now I have to follow the right procedure.

And I still have more inquiries concerning isolated smps… first should I start a new thread or I may just continue with this?

 

You just start a new thread and this thread will be close.