I want to design two full bridges for a dc-dc converter and dc-ac inverter of a 1.5kva inverter how many mosfet should I put in each bridge as I have heard other saying that there should be a combination of four groups of mosfets .In each group there will be 8 mosfets in parallel.Some are saying that only 4 mosfets can do for each bridge.
Depend up your load target application and wich Mosfet device are you using.
You can even use a single one if its characteristics are enought to fit requirements of IMAX VMAX and SOA.