Microinverter, photovoltaic system, and control method

Abstract

A micro inverter, a photovoltaic system and a control method are provided. The micro inverter includes a controller, a primary H-bridge, a transformer, a bi-directional switch leg, and a capacitor leg An input terminal of the primary H-bridge is connected to a direct-current power supply, two output terminals of the primary H-bridge are respectively connected to two terminals of a primary side of the transformer, two terminals of a secondary side of the transformer are respectively connected to an intermediate terminal of the bi-directional switch leg and an intermediate terminal of the capacitor leg, and the bi-directional switch leg and the capacitor leg are connected in parallel. The controller is configured to switch a control mode of the primary H-bridge and the bi-directional switch leg in a case that a phase of a grid voltage is an odd multiple of 0.25π in each cycle.