Output Voltage in Three-Phase Pulsewidth-Modulated Inverters

A theoretical analysis of pulsewidth control in three-phase pulsewidth-modulated inverters, is presented. Two general classifications of commutation schemes are discussed with respect to controllability of output voltage and commutation requirements. It is shown that for one scheme the output waveform is always defined regardless of load conditions but for the other scheme the output waveform is dependent on the load. A method of analysis is described whereby the output voltage, in the latter case, can be determined for sinusoidal load currents. Another method is then introduced whereby these results can be extended to applications with nonsinusoidal load currents.