Improved main circuit structure of photovoltaic synchronization inverter

Abstract

The invention discloses an improved main circuit structure of a photovoltaic synchronization inverter. The improved main circuit structure comprises a photovoltaic (PV) battery board, a capacitor Cin, distributed capacitors C1 and C2, a non-isolation direct-current / direct-current (DC / DC) converter, a capacitor C, an H bridge consisting of power switching devices V1, V2, V3 and V4, and diodes D1, D2, D3 and D4 which correspond to one another one to one, an afterflow loop on the voltage positive half circle of a power grid consisting of a power switching device V5 and diodes D5 and D7, an afterflow loop on the voltage negative half circle of the power grid consisting of a power switching device V6 and diodes D6 and D8, a filter circuit consisting of inductors Lf1 and Lf2 and a capacitor Cf,and a common mode resistant voltage filter H-bridge capacitor group consisting of capacitors C3, C4, C5 and C6. A synchronization inversion circuit for executing the improved main circuit structure has the advantages of capability of effectively restraining common mode voltage / current, high inversion efficiency, small volume, light weight, low electromagnetic noise and the like.

Description

technical field [0001] The invention relates to a grid-connected inverter circuit, in particular to an improved photovoltaic grid-connected inverter main circuit structure, which can be used for photovoltaic grid-connected power generation, communication power supply and other devices. Background technique [0002] Non-isolated grid-connected inverters have the advantages of small size, light weight, low cost, and high efficiency, and have attracted widespread attention from the industry. However, due to the distributed capacitance of the photovoltaic panel to the ground, the high-frequency common-mode voltage generated by the power switching device of the main circuit of the photovoltaic grid-connected inverter acts on the distributed capacitance, resulting in a relatively large gap between the photovoltaic panel and the ground. A large leakage current is generated, and the leakage current even exceeds the range specified by the relevant standards. The generation of high-f...

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Problems solved by technology

The main circuit structure can effectively suppress the above-mentioned common-mode leakage current, and its common-mode leakage current path is as follows: figure 2 shown, but there are also image 3 The peak common-mode leakage current shown (the upper side is the common-mode voltage waveform, and the lower side is the common-mode current waveform), the amplitude of the peak common-mode leakage current accounts for more than half of the overall common-mode leakage current amplitude, which has a considerable impact

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