FIVE-LEVEL LOW-COMMON-MODE LEAKAGE CURRENT SINGLE-PHASE PHOTOVOLTAIC GRID-CONNECTED INVERTER AND PHOTOVOLTAIC GRID-CONNECTED SYSTEM

摘要

Provided are a five-level low-common-mode leakage current single-phase photovoltaic grid-connected inverter and a photovoltaic grid-connected system using said inverter. The inverter comprises an H-bridge circuit (2), an AC bypass switching circuit (3), and a DC clamp switching circuit (4). The H-bridge circuit is connected between a DC link and an electrical grid/load; the AC bypass switching circuit is connected between the two output terminals of the H-bridge; the DC clamp switching circuit is connected between the capacitor midpoint of the DC link and the output terminal of the H-bridge circuit. The H-bridge circuit comprises a power switch tube S1, a power switch tube S2, a power switch tube S3, and a power switch tube S4; the AC bypass switching circuit comprises a power switch tube S5 and a power switch tube S6; the DC clamp switching circuit comprises a diode D1, a diode D2, a power switch tube S8, and a power switch tube S7. The inverter and photovoltaic grid-connected system are capable of giving full play to the advantage of five levels, improving the performance of the inverter and effectively suppressing common-mode leakage current.