Single-phase non-isolation type photovoltaic grid-connected inverter and control method

The invention discloses a single-phase non-isolation type photovoltaic grid-connected inverter and a control method. The photovoltaic grid-connected inverter comprises a full-bridge circuit, a control circuit and a fly-wheel diode, wherein the control circuit is used for controlling conduction and cut-off of all switching tubes in the full-bridge circuit so as to convert direct current voltage generated by a photovoltaic array of the full-bridge circuit to sine wave voltage required for grid connection; and the fly-wheel diode is used for providing a fly-wheel loop so as to thoroughly disconnect the input side from a power grid. The photovoltaic grid-connected inverter can effectively inhibit common-mode current (namely drain current) of the single-phase non-isolation type photovoltaic grid-connected inverter and improve the electrical energy conversion efficiency of the inverter.