A SINGLE-PHASE GRID CONNECTED TRANSFORMERLESS PHOTOVOLTAIC INVERTER

摘要

The single-phase grid connected transformerless photovoltaic inverterfor feeding power from a photovoltaic (PV) array to a single phase power grid. The inverter comprising: a plurality of semiconductor switches (S1-S6) connected in a HERIC configuration and at least two additional semiconductor switches (S7 and S8), wherein each of the switched are conducted by using a PWM modulation strategy; at least two filter inductors (LA and LB) provided in a symmetric configuration which attenuates at least one switching frequency component in a grid current; a first DC link capacitors (Cdc1) for said PV array and a second DC link capacitor (Cdc2) for a DC-DC converter. The DC-DC converter is energized only when said PV array voltage (Vdc1) falls below a peak grid voltage (Vgpk), and thereby generate an extended input voltage (Vdc2) using the second DC link capacitor so that a total DC link voltage (Vdc1 + Vdc2) greater than saidpeak grid voltage (Vgpk).