In the last article we learned how to generate sine wave pulse width modulation or SPWM though Arduino, we are going to use the same Arduino board to make the proposed simple pure sine wave inverter circuit.The design is actually extremely straightforward, as shown in the following figure.
You just have to program the arduino board with the SPWM code as explained in the previous article, and hook it up with some of the external devices.
Pin#8 and pin#9 generate the SPWMs alternately and switch the relevant mosfets with the same SPWM pattern.
The mosfst in turn induce the transformer with high current SPWM waveform using the battery power, causing the secondary of the trafo to generate an identical waveform but at the mains AC level.
The proposed Arduino SPWM inverter circuit could be upgraded to any preferred higher wattage level, simply by upgrading the mosfets and the trafo rating accordingly.
In the diagram the Arduino board could be seen supplied from a 7812 IC circuit, this could be built by wiring a standard 7812 IC in the following manner. The IC will ensure that the input to the Arduino never exceeds the 12V mark, although this might not be absolutely critical, unless the battery is rated over 18V.
If you have any questions regarding the above SPWM inverter circuit using a programmed Arduino, please feel free to ask them through your valuable comments.
Image of SPWM waveform as obtained from the above Arduino inverter design (Tested and Submitted By Mr. Ainsworth Lynch)
For the Program Code please visit the following link:
Arduino SPWM Generator Circuit
Since an Arduino board will produce a 5V output, it may be not be an ideal value for driving mosfets directly, therefore an intermediate BJT stage may be required for raising the gate level to 12V so that the mosfets are able to operate correctly without causing unnecessary heating up of the devices,. The updated diagram can be witnessed below:
While using the above configuration make sure that the Arduino code is appropriately modified by interchanging all "HIGH" inclusions with "LOW" and vice vesra.