Photovoltaic grid-connected inverter

The utility model discloses a photovoltaic grid-connected inverter which comprises a voltage boost circuit, a sine half-wave circuit, a commutation circuit and a control circuit. The voltage boost circuit, the sine half-wave circuit and the commutation circuit are connected successively, and are controlled by the control circuit. When the input DC voltage is lower than an operation voltage of the sine half-wave circuit, the control circuit controls the boost voltage for being switched on for performing voltage boost to the input DC voltage, thereby supplying enough operation voltage for the sine half-wave circuit. When the input DC voltage is larger than or equal with the operation voltage of the sine half-wave circuit, the control circuit controls the voltage boost circuit in a switched-off state The input DC voltage directly arrives at the sine half-wave circuit through the voltage boost circuit. The inverter has the following advantages: satisfying a requirement of wide variation range of DC voltage input from the inverter, settling a problem of common-mode current in the circuit, reducing EMI in the circuit, reducing high-frequency switch loss and inductance loss, and improving the operation efficiency of the whole inverter.