Classification of Grid Connected Transformerless PV Inverters with a Focus on the Leakage Current Characteristics and Extension of Topology Families

Grid-connected transformerless photovoltaic (PV) inverters (TPVIs) are increasingly dominating the market due to theirhigher efficiency, lower cost, lighter weight, and reduced size when compared to their transformer based counterparts. However,due to the lack of galvanic isolation in the low voltage grid interconnections of these inverters, the PV systems becomevulnerable to leakage currents flowing through the grounded star point of the distribution transformer, the earth, and thedistributed parasitic capacitance of the PV modules. These leakage currents are prohibitive, since they constitute an issue forsafety, reliability, protection coordination, electromagnetic compatibility, and module lifetime. This paper investigates a widerange of multi-kW range power rating TPVI topologies and classifies them in terms of their leakage current attributes. Thissystematic classification places most topologies under a small number of classes with basic leakage current attributes. Thus,understanding and evaluating these topologies becomes an easy task. In addition, based on these observations, new topologieswith reduced leakage current characteristics are proposed in this paper. Furthermore, the important efficiency and costdetermining characteristics of converters are studied to allow design engineers to include cost and efficiency as deciding factorsin selecting a converter topology for PV applications.

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Cite this article

[IEEE Style]

Z. Ozkan and A. M. Hava, "Classification of Grid Connected Transformerless PV Inverters with a Focus on the Leakage Current Characteristics and Extension of Topology Families," Journal of Power Electronics, vol. 15, no. 1, pp. 256-267, 2015. DOI: 10.6113/JPE.2015.15.1.256.

[ACM Style]

Ziya Ozkan and Ahmet M. Hava. 2015. Classification of Grid Connected Transformerless PV Inverters with a Focus on the Leakage Current Characteristics and Extension of Topology Families. Journal of Power Electronics, 15, 1, (2015), 256-267. DOI: 10.6113/JPE.2015.15.1.256.