SMPS 220V AC to 13.5 V DC

[vudiepdh1]

Hi every one !!
I want to design a circuit ( input 220V AC, output 13.5V Dc ) to charge for battery 12V Dc 100Ah using SMPS (boost mode ).
I need some idea to do it .
And i need some fomule to calculate SMPS transformer in this case ?
Thanks !

 

[Tahmid]

Hi,
It depends on the rate of charge you plan. Considering 0.1C (1/10 th of battery rated amperage), ie, 10A, you need a power supply capable of supplying 13.5V 10A. This is 135W of output power. You could use flyback or forward here, although at this power, you should look towards half-bridge or two-switch forward.

For half-bridge, you need a HF oscillator (SG3525 for example) and hi-lo side MOSFET driver (or IGBT driver, depending on whether you use MOSFET or IGBT, but MOSFET will do fine at this power), eg IR2110,L6385, etc.

Then the half-bridge transformer, output rectifiers, filter and feedback loop.

For MOSFET drive, you may opt to use pulse transformer.

Other things you have to keep in mind is current limiting. You could use foldback current limiting to ensure that the battery does not draw too much current.

And you certainly need short circuit protection.

Then the battery monitor. You can use microcontroller or comparators to check if the battery has reached 13.4-13.5v and then change the duty cycle of the oscillator to change output to about 12-12.5v for battery "float" or "trickle" charge, or you could stop charging completely.

I suggest you go through books by Marty Brown and Raymond Mack, where there are examples of half-bridge circuits and plenty of formulae for transformer, semiconductor, feedback, etc.

Go through these for some help (with transformer calculations):
**broken link removed**
**broken link removed**

Hope this helps.
Tahmid.

 

[mmrsharif]

Dear Tahmid,

Thank u very much for the link. i was looking for this for long time. once again thanks for share.

what is the impact of different driver circuit on ferrite transformer size?

regards
sharif

Hi,
............
Go through these for some help (with transformer calculations):
**broken link removed**
**broken link removed**

Hope this helps.
Tahmid.