This may seem like a stupid question, I thought I knew the answer to this but I think there is more than one answer to it and the question is to "clearly explain the function of an oscillator within an inverter circuit"
My initial thought was that it provides commutation to switch on and off switches alternatively like thyristors for example.
However I know that it's possible to create a true sinewave using positive feedback although this is very difficult so I know there is a big gap in my knowledge so may'be someone can think of another reason for oscillations? I can't think of another one at the moment.

 

The electricity in your home is AC at 60Hz in North America or 50Hz elsewhere. It is a sine-wave.

An inverter uses the power from a huge battery to create 50Hz or 60Hz at the same voltage as the electricity in your home but the waveform can be a square-wave for a very cheap circuit and many electronic products won't work from it, or the waveform can be a modified sinewave that is a little more complicated but nearly all products work from it, or the waveform can be a pure sine-wave which is made with a complicated circuit.

The oscillator in the inverter creates the 50Hz or 60Hz.

If you use a sine-wave oscillator driving a linear power amplifier then the amplifier wastes a lot of power as heat. The battery current is double what a modern circuit would be.
A modern sine-wave inverter uses a high frequency voltage stepup circuit that has a tiny transformer and a rectifier to make high voltage DC. Then another high frequency high voltage circuit uses pulse-width-modulation to create a stepped sine-wave then a small high frequency filter smooths the steps into a pure sine-wave. The parts that operate at high frequency barely get warm because they switch on and off.

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Uncle $crooge

 

Also not that if you're going to build an inverter or design an electrical system that uses one like a UPS or alternative energy supply use as high as DC input voltage as you can. Ohm's law states that to transmit the more power you need to increase either the current or the voltage. Increasing the current leads to large losses in the cables which will need to be thick bulky and expensive. I'd strongly recommend using 48V as it's too low to electricute you (unless you have really damp skin so keep away from water) and the current that delivers the same power is one quarter of that at 12V.

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Can you refer me some websites so I can learn in more detail....

 

Try Wikipedia, look up Inverter. Google and Wikipedia will reduce your need to ask questions here by a huge amount and give you more detailed information and reading refrences. Wikipedia in particular has a larger number of articles on electronic circuits of every kind.

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