Evaluation of Selective Harmonic Elimination and sinusoidal PWM for single-phase DC to AC inverters under dead-time distortion

The switch-mode operation of dc to ac inverters produces undesirable harmonics in the voltage and current outputs. Pulse Width Modulation (PWM) schemes based on Selective Harmonic Elimination (SHE) and carrier-based modulation are commonly used to address the harmonic reduction problem, and to provide adjustable inverter output fundamental components. The implementation of each scheme requires introduction of dead-time delays in the power switches of each inverter leg to cater for nonzero switching times of power semiconductors. In this paper we investigate the effect of dead-time distortion on the performance of SHE and sinusoidal PWM techniques for single phase dc to ac inverters with unipolar voltage switching. The modulation schemes are evaluated based on the harmonic distortions in the output currents and voltages, and on the power efficiencies when the inverters are operated at comparable switching frequencies.