Improved modulation techniques to eliminate leakage ground currents in three-phase photovoltaic systems

Nowadays transformerless PV converters are widely used in the energy conversion stage of a PV plant, because their good characteristics regarding efficiency, size, cost and weight. The main problem in transformerless PV systems is the common mode voltage variations that can generate leakage ground currents through the parasitic capacitance formed between the PV panels and ground. This paper comparisons the performance characteristic of conventional space vector PWM (SVPWM), AZSPWM, NSPWM and RSPWM. Based upon that, an improved AZSPWM scheme is proposed. Theoretical analysis is verified via simulation by means of MATLAB/SIMULINK.