Single-phase three-level photovoltaic inverter system

The invention provides a single-phase three-level photovoltaic inverter system which comprises six switch devices, each switch device is inversely connected with a diode in parallel, and the second switch device Q2, the third switch device Q3, the fourth switch device Q4, the sixth switch device Q6 and the fifth switch device Q5 are connected in sequence in series. A direct-current power source is connected in series with the first switch device Q1, and the other end of the first switch device Q1 is connected with the joint point of the second switch device Q2 and the third switch device Q3. High-frequency voltage at the input terminal is avoided, and efficient conversion is achieved at the same time. By means of the single-phase three-level photovoltaic inverter system, a short follow-current loop can be provided for an inversion inductor, the follow-current loop is completely separated from the direct-current bus side, high-frequency interference of the direct-current input side is avoided, meanwhile a reactive power switching loop is not arranged between the follow-current loop and the direct-current loop, and therefore efficiency of a photovoltaic inverter is greatly improved.