i have made a battery charger successfully with a maximum output of 20A. i used 20A transformer in it but it is too bulky and having larger in size and having cost double than the original circuit... so i want to replace the transformer with an Electronic circuit....
How should i design its schematic ... kindly help me... formulatic evaluation and related links will be very appreciated.
Basically you don't - you already have the best solution for a battery charger.
To make it smaller you 'could' make it switch-mode, but that would require much more complex electronics, a MUCH higher level of skill, and a specially made transformer.