Leakage current analysis of a single-phase transformer-less PV inverter connected to the grid

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  • Lin Ma
  • F. Tang
  • F. Zhou
  • X. Jin
  • Y. Tong

Abstract

Due to the large surface of the PV generator, its stray capacity with respect to the ground reaches values that can be quite high. When no transformer is used in a grid-connected PV system, common-mode current, which caused by the common mode voltage, can flow through the stray capacitance between the PV array and the ground. It is quite harmful to the body safety and PV system. In order to avoid leakage current, different inverter topologies that generate no varying common-mode voltages, such as bipolar pulse-width modulation (PWM) full-bridge topology, NPC topology have been proposed. From the safety and energy saving viewpoint, it is necessary to develop a higher efficiency topology. In this paper, the generation mechanism of common mode current is discussed. Then different methods used to eliminate the leakage current are compared. Finally, the full-bridge which generates no varying common-mode voltage and requires the same low-input voltage as the bipolar PWM full-bridge is given. The proposed topology has been verified in the simulation based on MATLAB with satisfactory results.
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Details

Due to the large surface of the PV generator, its stray capacity with respect to the ground reaches values that can be quite high. When no transformer is used in a grid-connected PV system, common-mode current, which caused by the common mode voltage, can flow through the stray capacitance between the PV array and the ground. It is quite harmful to the body safety and PV system. In order to avoid leakage current, different inverter topologies that generate no varying common-mode voltages, such as bipolar pulse-width modulation (PWM) full-bridge topology, NPC topology have been proposed. From the safety and energy saving viewpoint, it is necessary to develop a higher efficiency topology. In this paper, the generation mechanism of common mode current is discussed. Then different methods used to eliminate the leakage current are compared. Finally, the full-bridge which generates no varying common-mode voltage and requires the same low-input voltage as the bipolar PWM full-bridge is given. The proposed topology has been verified in the simulation based on MATLAB with satisfactory results.
Original languageEnglish
Title of host publicationProceedings of IEEE International Conference on Sustainable Energy Technologies, ICSET 2008
Number of pages5
PublisherIEEE
Publication date2009
Pages285-289
ISBN (Print)978-1-4244-1887-9
DOI
Publication statusPublished - 2009
Publication categoryResearch
Peer-reviewedYes
EventIEEE International Conference on Sustainable Energy Technologies, ICSET 2008 - , Singapore
Duration: 24 Nov 200827 Nov 2008

Conference

ConferenceIEEE International Conference on Sustainable Energy Technologies, ICSET 2008
LandSingapore
Periode24/11/200827/11/2008
ID: 18186601