A novel efficient structure applied to non-isolated single-phase photovoltaic grid inverters

Abstract

To suppress the common mode current flowing into the grid effectively, this paper presents a novel active clamping inverter topology with non-isolated single-phase photovoltaic grid inverters. This topology can provide freewheeling path and separate solar panels from the grid at the freewheeling stage. In addition, a series resistor in the clamping channel of the new structure is added, which can effectively reduce the clamp switch conduction loss, even suppress the clamping channel's influence on common mode current. Simultaneously, since the body diode's reverse recovery performance is poor, the wheeling diode is applied into the freewheeling path. The working principle of the topology, the driving logic and the common-mode current equivalent circuit model are all analyzed in detail in this paper. And this paper expounds the function of series resistance, and enumerates common mode current suppression effect at different resistance. The topology's features such as low common mode current, high efficiency and low grid current waveform distortion(THD) are also verified in simulation experiments.