A low leakage current grid-connected inverter

Abstract

The invention discloses a low-leakage-current grid-connected inverter which comprises six switching tubes T1-T6 and a filter inductor L, wherein T1 and T4 form a two-way switch, so that the two ends of a grid are connected with an anode of a direct current power supply via the switching tubes T1 and T4; inverse parallel diodes of T3, T5 and T2 and L form a current output Buck converter to provide positive half-wave grid-connected current; inverse parallel diodes of T2, T6 and T5 and L form another current output Buck converter to provide negative half-wave grid-connected current; a cathode of the direct current power supply is connected with emitters of the switching tubes T3 and T6; switching motion of the switching tubes is controlled by corresponding control circuits; and T3 and T6 are driven by high-frequency signals. According to the inverter, ground leakage current of the inverter can be effectively inhibited; the inverter has the advantages of high efficiency and simple modulation method; and the invention is applicable to inversion power supply systems with stricter leakage current magnitude limitation, such as a transformerless photovoltaic grid-connected inverter.

Description

technical field [0001] The invention relates to the technical field of DC-AC inverter, in particular to a single-phase grid-connected inverter. Background technique [0002] As countries all over the world attach importance to the development and application of new energy, new energy technologies such as photovoltaics have been extensively researched and applied. In the photovoltaic power generation system, the DC power generated by the photovoltaic array is generally converted into AC power by the grid-connected inverter to supply the load or merge into the grid. Grid-connected inverters can be divided into transformer-based and transformer-less grid-connected inverters. The existence of the power frequency transformer in the grid-connected inverter with transformer greatly increases the volume and weight of the grid-connected inverter, which is not suitable for small and medium power applications. variable system efficiency and power density. However, the transformerles...

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Problems solved by technology

However, in this topology, four switches are driven by high-frequency signals. In the positive and negative half-waves of the power grid, two switching tubes are controlled by the SPWM control method. The switching loss is large, and two filter inductors are included at the same time, which is large in size and high in cost.

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