Dear Saugata,
please read my comments pointwise:


Quote Originally Posted by sougata
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.
When one is making Inverter/UPS then the transformer and MOSFETS
have to handle this currents and I have seen atleast 3in parallel to do this.
I think It is OK for 500VA and for 1KVA one has to use 24V battery for same
purpose. Higher rated systems are using batteries 48V or even 110V!!!

2. Frequency has to be kept high (ferrites) consider the switching losses of the primary MOSFETs.
Frequency has been optimised to 40-60KHz for considering this aspect.
I would like to use more than 100Khz if possible but then MOSFETs would be
beyond reach.

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.
My design has 3 switching stages. a)First for conversion to 12V from 230V(SMPS), second a simple Inverter to convert 12Vdc to 300V dc dual supply and lastly the Sinewave converter with half bridge for direct output.
SMPS is based on SG3525 and dc to dc also same but they can have analog
control inputs with additional PWM from Microchip instead of DAC.The last converter is entirely based on Microchip and same chip can used for other indication or control functions. One has to consider the entire system development and how to make optimum use of available resources. It is just
not possible to use one PIC for all functions reqd.

4. Microchip has a very good appnote on such type of design.
Please do send link for that design.

5.If you are using PBP then this forum will help you out in solving problems.
Im not aware of PBP. I am doing programming in Assembly and use a
program to convert it in code.

6.One of my laboratory power supplies runs on a PIC for a Buck regulator.
Im very interested know about it.

7.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
Please visit cosmo ferrite website. They have dealers all over India and
Kolkata must be having some. If U want some hard to get size then I can
help. But for regular supplies the company will gleadly contact U.
I think I have missed Ur reply due to incorrect setting of intimation. Im
sending U private email for details.
Thanks,
psdayama