A zone-based modulation strategy to reduce the leakage current in transformerless PV inverters

Abstract

The reduction of the leakage current in transformerless grid-interfaced inverter topologies is essential to meet the requirements of the safety standards as well as to mitigate electromagnetic interference. The conventional PWM schemes for multilevel-inverters (MLIs) either generate a high frequency leakage current or underutilize the resources of the multilevel inverters. In this paper, an asymmetrical 1 inverter topology and its modulation scheme are presented for the PV system. Without any additional switching resources, the proposed modulation strategy achieves the avoidance of high frequency components in the voltage impressed across the PV parasitic capacitor. Furthermore, a dual-mode boosting stage is integrated into the proposed multilevel inverter configuration in such a way that, it is capable of synthesizing thirteen distinct voltage levels while achieving a voltage boosting factor of three. Simulation results verifying the operating principle of the proposed power converter are presented, which employs the proposed modulation technique.