On PWM Strategies and Current THD for Single- and Three-Phase Cascade H-Bridge Inverters with Non-Equal DC Sources
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Date
2019-01-30
Authors
Akhmetov, Zhansen
Hammami, Manel
Grandi, Gabriele
Ruderman, Alex
Journal Title
Journal ISSN
Volume Title
Publisher
MDPI
Abstract
Cascade H-bridge (CHB) inverter is an attractive choice for integration of DC sources of
different nature, e.g., for distributed generation with energy storage, photovoltaic generation, etc. In
general, non-equal DC voltage sources can affect the total harmonic distortion (THD) of the CHB by
introducing undesirable low-frequency subharmonics. This paper investigates different level-shifted
(LS) and phase-shifted (PS) pulse width modulation (PWM) strategies for single- and three-phase
cascade H-bridge inverters with non-equal DC sources from the load current THD minimization
perspective. The best current quality is provided by LS PWM, as reported in the literature. The paper
provides a simple time domain explanation of LS PWM superiority. However, PS PWM may be
a preferable choice for practical applications due to fair power and loss sharing across individual
H-bridges. The paper explains how to obtain the best current quality by PS PWM carriers’ order
arrangement (DC sources switching sequence selection).
Description
Keywords
multilevel inverters, total harmonic distortion, level-shifted PWM, phase-shifted PWM
Citation
Akhmetov, Z.; Hammami, M.; Grandi, G.; Ruderman, A. On PWM Strategies and Current THD for Single- and Three-Phase Cascade H-Bridge Inverters with Non-Equal DC Sources. Energies 2019, 12, 441.