What Thannara is saying, is that a 3Kva sinewave inverter project is a very complex project, as you may have already seen if you have repaired such a unit.
Not only the electrical hardware design is a challenge, you will require significant software development and -very important- the mechanical design which will allow to dissipate all the heat and carry the very large currents involved.
On this last point; some simple calculation:
Assuming a generous 80% efficiency, for 3000 watts output, your power input will be 3750 watts.
A 24 volt nominal battery bank will see its voltage drop as the battery is depleted. Let's say you want to cut out at 18 volts. Therefore the input current will be 208 amps average. The current however, will be pulsed, and depending how well you have decoupled it, the peak pulses will be much higher than that.
In conclusion: This is a major project that you have to design in small pieces. Design each piece and then ask questions about that particular piece.
Heck, if you do a forum search about the IRF2110 Mosfet driver, you'll see dozens and dozens of threads related to simply driving a Mosfet correctly.