Hi Dayama,

What you are proposing is a dual conversion design. When you have a battery bank of greater voltage it makes sense other wise for a 12/24 volt system consider this.

1. The Primary current will in the order of 50 AMPs so it is necessary to use copper bands for the primary windings.

2. Frequency has to be kept high (ferrites) consider the switching losses of the primary MOSFETs

3. You have two different switching stage so a single PIC may complicate your programming issues.Of course you can use a ready made SMPS controller like the SG3525 but then this forum may not be the right place to discuss.

4. Microchip has a very good appnote on such type of design.

If you are using PBP then this forum will help you out in solving problems.

One of my laboratory power supplies runs on a PIC for a Buck regulator.

We get only a limited supply (not all models) of cosmo ferrites so it is beyond my scope of experiment. However I would definately like to meet you while I am in Mumbai.Send me a private email if you are interested.

Regards

Sougata