Open AccessEffects of modulation techniques on leakage ground currents in a grid‐tied transformerless HB‐NPC inverter
Author(s) -
MartinezGarcia Juan Felipe,
MartinezRodriguez Panfilo Raymundo,
Escobar Gerardo,
VazquezGuzman Gerardo,
SosaZuñiga Jose M.,
ValdezFernandez Andres A.
Publication year - 2019
Publication title -
iet renewable power generation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.005
H-Index - 76
eISSN - 1752-1424
pISSN - 1752-1416
DOI - 10.1049/iet-rpg.2018.5471
Subject(s) - pulse width modulation , leakage (economics) , electronic engineering , inverter , common mode signal , engineering , modulation (music) , voltage , computer science , electrical engineering , control theory (sociology) , physics , acoustics , analog signal , control (management) , digital signal processing , artificial intelligence , economics , macroeconomics
In this paper, a comparative study of modulation techniques used in a transformerless H‐bridge neutral point clamped (HB‐NPC) multilevel inverters is presented. Transformerless inverters, usually found in photovoltaic (PV) applications, are more efficient and economically affordable than isolated systems. Nevertheless, they may cause leakage ground currents. The latter are produced by the stray capacitances formed between the PV panel frame and the ground path. There are different ways to overcome the leakage ground current issue in transformerless topologies, for instance using topologies that generate almost zero leakage currents, by using adequate modulation techniques, by inserting additional filters, and by using adequate control schemes, among others. The comparative study, considers five modulation strategies, namely, level‐shifted pulse‐width modulation (PWM), phase‐shifted PWM, three‐level PWM, two sectors hybrid PWM and six sectors hybrid PWM. As it will be demonstrated through the common‐mode model analysis, the three last modulations strategies are aimed at alleviating the leakage ground current issue. In this study, the two sectors hybrid PWM and the six sectors hybrid PWM are proposed. These modulation techniques lead to obtaining five output voltage levels keeping the RMS value of the leakage currents bounded for the transformerless HB‐NPC inverter.