Power converter, photoelectric system, and operating control method

Abstract

The invention relates to an electric converter, a photovoltaic system, a method, and an apparatus. The converter consists of an electric converter circuit, a switching device, and a controller, and comprises N phases, where N equals 2 or 3. The input of the opposite circuit is connected to a direct current power source, and the electric converter converts the direct current output from the direct current power source into alternating current. The switching unit comprises at least two stages: the first-stage switching unit and the second-stage switching unit. The first-stage and second-stage switching units each consist of N separate switching units, and these N switching units are connected in series with N phases. The output of the power converter circuit is connected to the AC power grid via the first-stage switching unit and the second-stage switching unit connected in series. The controller is configured so that: when the converter circuit is connected to the AC power grid, it pre-controls N switches in the second-stage switching unit to be switched on simultaneously, and then sequentially controls N switches in the first-stage switching unit to be switched on one after another. When the converter is connected to the grid, the surge currents carried by a portion of the switching unit can be reduced.