How to Build a 500W Pure Sine Wave Inverter for Final Year Project (Digital/Analog)

I am a student working on my final year project.

I need assistance on how to build a pure sine wave inverter (digital or analog) of about 500 W. I will be glad if anyone can help me out.

There are several ways to do this starting with 12 VDC. To me the simplest way is a push-pull audio amp driving a center tapped 12.6 volt to 240 volt transformer. The disadvantage of this is that the efficiency is only about 50% and a large 50 Hz transformer is required. To deliver 500 watts of AC 500 watts is dissipated in the transistors.

yeah, i fully understand that , i really appreciate your reply.
may be i need be more specific this time (the first message was done in a haste.
i want to design a 5oow pure sine wave inverter and would prefer a tri level pulse width modulator with a battery charging option when it is connected to power.
i just want to get the circuit design, and a little hint on how the parts function will be great.
thanks so much.