PROJECT TITLE :

Simple Time Averaging Current Quality Evaluationof a Single-Phase Multilevel PWM Inverter - 2016

ABSTRACT:

This paper addresses theoretical calculation of one-section multilevel pulsewidth modulation (PWM) inverter current total harmonic distortion (THD). Analytical approach introduced in late Eighties for a two-level inverter is generalized for an arbitrary level count for a single-phase inverter. Although the obtained closed-form piecewise analytical solutions assume (infinitely) giant ratio of switching and elementary frequencies and pure inductive load, they're practically very correct for the ratios of (apparent) switching and fundamental frequencies larger than 25-thirty and inductance-dominated loads. Along with strict mathematical solutions, simple correct Bessel perform approximation and hyperbolic average trend one are recommended. The formulas clearly reveal a single-phase PWM inverter current THD dependence on modulation index for an arbitrary voltage level count and are easily changed to hide grid-connected cases.