A novel SVPWM method with periodically-balanced zero-sequence voltage impulse for three-phase three-level photovoltaic inverters

The modulation technique is an effective measure to suppress the leakage current in three-phase three-level transformer-less photovoltaic systems. This paper further analyzes the intrinsic relationship between the common mode voltage and the zero-sequence voltage of three-phase three-leg three-level inverters, with a novel SVPWM method proposed. The presented algorithm makes the zero-sequence voltage impulse periodically balanced by using the small voltage vectors reasonably. Compared with the traditional SVPWM scheme, the proposed method can remarkably reduce the common mode voltage magnitude over all frequency. Besides, the algorithm requires small computational burden and is straightforward for an online implementation. Experimental results validate the effectiveness of the proposed SVPWM method.