V. CONCLUSIONS
Trapezoidal modulation technique has been implemented in
an AC to AC converter in order to reduce the harmonics in the
output of the converter. The Trapezoidal wave is suitable for
on-line computation and its waveform varies from a
rectangular wave to a triangular wave. Besides being easy to
realize and simulate, the controllability of trapezoidal
modulator is wide and versatile. The modulation technique
increases the fundamental output voltage up to 15% as
compared to conventional Sine PWM. The harmonics in the
output of AC to AC converter is also reduced to a large extent.
Minimum THD has been found to 5% during cyclo-inverter
operation for a frequency range of 500 to 750 Hz. During
cyclo converter operation it reduces to 1.2% for a frequency of
1 Hz. It is in the range of 1 to 2.5 % for a frequency range of
1 to 16.66 Hz which is generally recommended mode of
cyclo-converter. It is therefore advisable to use this technique
for cyclo-converter operation.