Digital control of actual grid-connected converters for ground leakage current reduction in PV transformerless systems

Giampaolo Buticchi, Davide Barater, Emilio Lorenzani, Giovanni Franceschini

Research output: Journal PublicationArticlepeer-review

90 Citations (Scopus)

Abstract

The design of a photovoltaic (PV) grid-connected converter usually comprehends a galvanic isolation between the grid and the photovoltaic panels. Recently, in low power systems, the galvanic isolation has been removed with the aim to increase efficiency and reduce the cost of the converter. Due to the presence of a parasitic capacitance between the photovoltaic cells and the metal frame of the PV panel, usually connected to earth, a high value of common mode current (i.e., ground leakage current) can arise. In order to limit the ground leakage current (which deteriorates the power quality and generates EMI), new converter topologies have been proposed. Their effectiveness is based on the symmetrical (ideal) commutations of the power switches and some of them adopt a further voltage level derived from a capacitive divider of the DC bus voltage. Unfortunately, in actual implementations, asymmetrical power switches transients and variations of this added voltage lead to higher ground leakage current with respect to the ideal case. After a review of the state of the art this paper investigates these two issues and presents a particular solution (based on digital control and PWM strategy) that, in conjunction with a compensation strategy of power switches actual commutations, guarantees low ground leakage current regardless the parameters tolerance of the power circuit. Simulation and experimental results confirm the effectiveness of the proposed solution.

Original languageEnglish
Article number6176216
Pages (from-to)563-572
Number of pages10
JournalIEEE Transactions on Industrial Informatics
Volume8
Issue number3
DOIs
Publication statusPublished - 2012
Externally publishedYes

Keywords

  • Digital control
  • photovoltaic systems
  • pulse width modulation
  • static power converters

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Information Systems
  • Computer Science Applications
  • Electrical and Electronic Engineering

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