As can be seen in the first diagram below, the configuration is a simple mosfet based designed for amplifying current at +/-60 volts such that the connected transformer corresponds to generate the required 1kva output. Q1, Q2 forms the initial differential amplifier stage which appropriately raises the 1vpp sine signal at its input to a level which becomes suitable for initiating the driver stage made up of Q3, Q4, Q5.
1KVA (1000 watts) Pure Sine Wave Inverter Circuit Diagram:
The mosfets are also formed in the push pull format, which effectively shuffles the entire 60 volts across the transformer windings 50 times per second such that the output of the transformer generates the intended 1000 watts AC at the mains level. For acquiring the intended pure sine wave output, a suitable sine input is required which is fulfilled with the help of a simple sine wave generator circuit. It is made up of a couple of opamps and a few other passive parts.
It must be operated with voltages between 5 and 12. This voltage should be suitably derived from one of the batteries which are being incorporated for driving the inverter circuit. The below given diagram shows a simple sine wave generator circuit which may be used for driving the above inverter circuit, however since the output from this generator is exponential by nature, might cause a lot of heating of the mosfets. A better option would be to incorporate a PWM based circuit which would supply the above circuit with appropriately optimized PWM pulses equivalent to a standard sine signal.
