Non-isolated clamping type three-phase Herbic photovoltaic inverter topology

Abstract

The invention relates to a non-isolated clamping type three-phase Heric photovoltaic inverter topology. The non-isolated clamping type three-phase Heric photovoltaic inverter topology is composed of atraditional three-phase bridge type inverter circuit, a three-phase follow current circuit and a clamping circuit. The three-phase freewheeling circuit is formed by six switching tubes through star connection, and the freewheeling circuit can enable the current of the inverter not to flow through a direct-current power supply in the freewheeling stage, thereby saving the feedback of energy, and improving the conversion efficiency of the inverter. The clamping circuit is composed of three direct-current capacitors and two clamping switch tubes. The three direct current capacitors divide the direct current source into four potential points of 0, 1 / 3, 2 / 3 and 1; two clamping switches are respectively added to 1 / 3 and 2 / 3 potential points, so that the common-mode voltage of the inverter in the follow current stage is clamped to 1 / 3 and 2 / 3 of the direct current input voltage, the amplitude of the common-mode voltage is reduced, the leakage current of the photovoltaic inverter is inhibited, and the safety of personnel and equipment in use is ensured.

Description

technical field [0001] The invention relates to a photovoltaic inverter topology, in particular to a non-isolated clamp type three-phase Heric photovoltaic inverter topology, which belongs to the technical field of power electronic DC-AC conversion. Background technique [0002] Photovoltaic inverters require high conversion efficiency, low cost, and can withstand the adverse effects of large fluctuations in the output voltage of photovoltaic cells, and the AC output of the inverter must also meet high power quality. Photovoltaic inverters can be divided into isolated type and non-isolated type according to whether they have an isolation transformer or not. The isolated photovoltaic inverter realizes the electrical isolation between the grid and the battery panels, ensuring the safety of operators and equipment, but it is large in size, heavy in weight, high in cost, and low in system conversion efficiency. The non-isolated photovoltaic inverter does not contain a transform...

AI Technical Summary

Problems solved by technology

The isolated photovoltaic inverter realizes the electrical isolation between the grid and the battery panels, ensuring the safety of operators and equipment, but it is large in size, heavy in weight, high in cost, and low in system conversion efficiency

The non-isolated photovoltaic inverter does not contain a transformer in its structure, so it has the advantages of small size, light weight, and low cost. However, it lacks a transformer for electrical isolation. The inductor and the power grid form a common-mode loop, and with the high-frequency switching action of the power switching device, leakage current will be generated in the loop

The existence of leakage current will increase the harmonic content of inverter output current and increase electromagnetic interference, thereby reducing power quality, causing grid current distortion, and causing certain power loss. At the same time, leakage current also brings certain hidden dangers to the safety of operators , therefore, in order to ensure the safety of personnel and equipment, the leakage current must be suppressed within a certain range

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