An eight-switch tube transformerless photovoltaic grid-connected inverter circuit and control method

Abstract

The invention discloses an eight-switch tube transformerless photovoltaic grid-connected inverter circuit and a control method, which belong to the field of power electronics. The inverter controls the actions of eight switch tubes in the inverter circuit through a given switch tube drive signal. In the freewheeling phase, through the action of the switching tube and the diode D 1 , D 2 Constitute a zero-level freewheeling circuit, which can realize that the voltage of the freewheeling circuit during the freewheeling stage is half of the input voltage, so that the common mode voltage of the inverter is always kept at U dc / 2 remains unchanged, which can eliminate the high-frequency ripple of the common-mode voltage, thereby effectively suppressing the leakage current to the ground; and by building a new freewheeling circuit to change the freewheeling current path, so that the freewheeling path does not pass through the body diode with large conduction loss , which reduces the conduction loss; at the same time, compared with other mid-point clamping methods, there is no switch tube in this topology that is always in high-frequency working state, which reduces switching loss and improves efficiency. It has simple topology, high efficiency, and simple modulation strategy. Etc.

Description

technical field [0001] The invention belongs to the technical field of power electronic photovoltaic grid-connected power generation, and specifically relates to an eight-switch tube transformerless photovoltaic grid-connected inverter circuit and a control method. Background technique [0002] With the depletion of traditional energy sources, it is imminent to seek new energy sources. Solar energy has become the first choice for new energy workers due to its endless and safe and reliable features. The single-phase non-isolated photovoltaic grid-connected inverter has the advantages of small size, light weight, low cost, simple structure and improved system efficiency because the transformer is removed, and it has become one of the mainstreams of research on photovoltaic grid-connected power generation systems. [0003] However, due to the removal of the transformer, the parasitic capacitance of the inverter to the ground and various filter inductors and filter capacitors i...

AI Technical Summary

Problems solved by technology

[0005] Aiming at the problem of large ground leakage current in single-phase non-isolated photovoltaic grid-connected inverters, the present invention proposes a high-efficiency, low-leakage current non-isolated eight-switch tube transformerless photovoltaic grid-connected inverter circuit

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