Effects of switching time on output voltages of a multilevel inverter used in high frequency applications

Employing multilevel inverters is a proper solution to reduce harmonic content of output voltage and electromagnetic interference (EMI) in high power electronic applications. In this paper, a new pulse width modulation method for multilevel inverters is proposed in which power devices´ on-off switching times have been considered. This method can be surveyed in order to analyze the effect of switching time on harmonic contents of output voltage in high frequency applications when a switching time is not negligible compare to a switching cycle. FFT calculation and analysis of output voltage waveforms and harmonic contents with regard to switching time variation are presented in this paper for a single phase (3, 5)-level inverters used in high voltage and high frequency converters. Mathematical analysis and MATLAB simulation results have been carried out to validate the proposed method.