Harmonic Reduction in Inverters by Use of Sinusoidal Pulsewidth Modulation

This paper presents a new technique for harmonic reduction in inverters using sinusoidal pulsewidth modulation. In this inverter, the output wave with sinusoidal pulsewidth distribution can be kept in maximum degree of symmetry, and so it offers excellent harmonic control in comparison with any other modulation technique. Detailed analysis shows that the harmonics lower than the ninth (or the thirteenth) are all less than one percent of the fundamental component when the number of pulses per half cycle is over seven (or nine). These results are confirmed by the theoretical data obtained from the natural sampling, and the experimental observations for single-phase full-bridge sinusoidal pulsewidth modulated (SPWM) inverters. It is concluded that by the use of this new technique it is quite easy to design an inverter with a distortion-free sinusoidal output.