Are you planning to build a high power inverter that would be powerful, robust, low cost and yet would be suitable for operating all your delicate household equipment? Right, then probably the present circuit is just what you might be looking for.
Please refer THE CIRCUIT DIAGRAM tp better understand how to make a 500 watt modified sine wave inverter, PWM controlled.
The design explained here is ofcourse not a pure sine wave inverter, yet still it fulfill most of the critria associated with sine wave inverters, simply because the design allows yu to optimize and set the pulses or ratherthe frequency of the output precisely to the RMS value of a standard sine waveform.
The above idea might look way too complicated as most of the modified sine wave inverters are, however you may be truly amazed to find that the proposed concept isso simple and very cleverly implemented.
Actually the circuit incorporates an ordinary IC 4093 for the required operations. Here the gates are configured as PWM generator and a couple of them are used as buffers.
The PWM section also includes a couple of gates, each wired up as square wave oscillators. However one of them is responsible of generating rapid rectangular waves while the earlier one generates oscillations suiting the basic 50 or 60 Hz frequency. The rapid frequency intervenes with the above basic frequency and trims them to values which closely match the standard sine AC waveforms, just what is expected from the design.