Discrete Fourier transform harmonic analysis of digitally-generated PWM waveforms which are distorted by switch dead time

摘要

A modified discrete-Fourier-transform method is applied to the harmonic analysis of PWM waveforms which are generated using digital techniques. This method simplifies the calculation of harmonic components, including subharmonics. The effect of dead time distortion caused by phase current polarity is examined in the presence of varying power factor and modulation index. This distortion is characterized by the amplitude change of the modulating frequency component and by determining a weighted total harmonic distortion.