Is MPPT of PV array possible if only converters are used and the connected load is a battery?
But i am unable to achieve mppt as well as current regulation. Is there any flaw in my system or approach?


The flaw is in your approach.  Putting a constant current into a battery implies establishing a constant power draw -- but "MPPT" stands for maximum power point tracking.

If a charging battery is the only load on your solar cell, the best you can hope for is to draw the maximum possible power from the cell (using MPPT) it is the cell that limits the power, and to regulate the current to the battery only when the cell can supply more power than the battery can absorb.

This is probably not possible without a combined battery charger/MPPT tracking algorithm that "understands" when it is limited by the cell, and when it is limited by the requirements of the battery.

On the bright side, with such a combined algorithm you'll only have one DC-DC converter.