Effect of the Modulation Index and the Carrier Frequency on the Output Vol Tage Waveform of the Spwm Voltage Source Inverter

In this paper, the effect of the modulation index and the carrier frequency on the harmonic contents of the output voltage waveform of the sinusoidal-pulse-width-modulated (SPWM) voltage-source inverter (VSI) is presented. Both, the modulation index and the carrier frequency are affecting the harmonic contents of the inverter output voltage waveform. The frequency spectrum, of the unwanted harmonics, are shifted towards higher frequency by increasing the carrier frequency. The total harmonic distortion (THD) factor of the inverter output voltage decreases as the modulation index, increases. For carrier frequencies, greater than a certain value, the THD factor doesn't change much by further increasing the frequency of the carrier signal.