In domestic grid connected PV applications a single phase converter is usually used. In such a low power plants it is possible to adopt converter topology with no galvanic isolation between the photovoltaic panels and the grid. The absence of a high or low frequency transformer permits to reduce power losses, cost and size of the converter. On the other side in presence of a galvanic connection a large leakage ground current could arise due to parasitic PV panel capacitance. This leakage current causes electric safety problems, an increase of EMI and a reduction of the power quality. This paper presents a converter topology based on unipolar PWM modulation able to minimize the leakage ground current locking the common output voltage to VDC/2 as the converters topology based on bipolar modulation do. Simulation results show the effectiveness of the proposed topology. Eventually a comparison of the power losses of the proposed architecture with respect to some established topologies is presented.
Unipolar PWM for transformerless grid-connected converters in photovoltaic plants / Barater, D.; Franceschini, G.; Lorenzani, Emilio. - ELETTRONICO. - (2009), pp. 387-392. (Intervento presentato al convegno IEEE ICCEP 2009 tenutosi a Capri (Italy) nel 2009-june) [10.1109/ICCEP.2009.5212026].