A nine-level grid-connected converter topology for single-phase transformerless PV systems

Giampaolo Buticchi, Davide Barater, Emilio Lorenzani, Carlo Concari, Giovanni Franceschini

Research output: Journal PublicationArticlepeer-review

178 Citations (Scopus)


This paper presents a single-phase transformerless grid-connected photovoltaic converter based on two cascaded full bridges with different dc-link voltages. The converter can synthesize up to nine voltage levels with a single dc bus, since one of the full bridges is supplied by a flying capacitor. The multilevel output reduces harmonic distortion and electromagnetic interference. A suitable switching strategy is employed to regulate the flying-capacitor voltage, improve the efficiency (most devices switch at the grid frequency), and minimize the common-mode leakage current with the help of a novel dedicated circuit (transient circuit). Simulations and experiments confirm the feasibility and good performance of the proposed converter.

Original languageEnglish
Article number6642109
Pages (from-to)3951-3960
Number of pages10
JournalIEEE Transactions on Industrial Electronics
Issue number8
Publication statusPublished - 1 Aug 2014
Externally publishedYes


  • Leakage current
  • multilevel systems
  • photovoltaic (PV) systems
  • pulsewidth modulation (PWM) inverters

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Electrical and Electronic Engineering


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