Three-phase four-leg inverter used for photovoltaic grid-connected power generation and photovoltaic grid-connected power generation system

The invention discloses a three-phase four-leg inverter used for photovoltaic grid-connected power generation. The input end of the inverter is connected with a photovoltaic array, and the output end is connected with a three-phase power grid; the inverter comprises three legs (a, b and c) which are connected with each other in parallel and a neutral legs (n) which is connected with the two ends of the three legs in parallel; each leg comprises two serially-connected switches (S1 and S4/S3 and S6/S5 and S2); the connecting point of every two serially-connected switches is of the output end of each leg; the neutral leg comprises two serially-connected switches (S7 and S8); the connecting point of the two switches (S7 and S8) forms the output end of the neutral leg; and the output end of the neutral leg is connected with a neutral line of the three-phase power grid. The invention also discloses a photovoltaic grid-connected power generation system comprises the inverter. The system has the characteristics of very high adaptability to the imbalance of a power grid and extremely low grid-connected current harmonic content.