| Summary: | The recent demand of renewable energy elevates rapidly. Inverter as one
equipment relates closely to the renewable energy sector gain more and more important
role by this condition. In a grid-connected system, the inverter should be able
to adjust its output voltage and frequency in synchronize with the grid. The issues
related to this is the output voltage and frequency resolution. Normally, in order to be
able to control its output parameters, an inverter employs specific switching strategies
such as sinusoidal pulse width modulation (SPWM).
In this research, a direct digital synthesis (DDS) is proposed in order to create
sinusoidal pulse width modulation (SWPM) that can meet the synchronization
requirements such as voltage and frequency. The DDS is digitally implemented using
low cost 16-bit digital signal controller. DDS is a technique to create various signal
based on lookup table. The ability to adjust its frequency output since using a counter
as an address to take some data form table. Meanwhile, the voltage adjustment is
obtained by multiplying the data from table with decimal in range 0 - 1.
A prototype has been built in the lab scale to verify the proposed system design.
Experiment results has shown that the voltage ranges of 47,2 - 246 V and frequency
resolution of 1 Hz can be achieved through the low cost controller. Another
result, the efficiency of inverter is above 82 %.
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