Main circuit topology of single-phase non-isolated photovoltaic inverter with follow current clamping switch

Abstract

The invention provides a main circuit topology of a single-phase non-isolated photovoltaic inverter with a follow current clamping switch. The main circuit topology of the single-phase non-isolated photovoltaic inverter with the follow current clamping switch comprises a single-phase full-bridge inverter, a clamping capacitor set, the follow current clamping switch, an LCL filter circuit and a resistor, wherein the follow current clamping switch is composed of a single-phase non-controlled rectifier bridge and two switch tubes, and the clamping capacitor set is composed of two input capacitors. According to the single-phase non-isolated photovoltaic inverter, the follow current clamping switch is additionally arranged at the alternating-current side of the full-bridge inverter, the follow current of the inverter can be made not to pass through an input power supply by the follow current clamping switch, the step that energy is fed back to the power supply is omitted, and the conversion efficiency of the non-isolated photovoltaic inverter is improved; in addition, one ends of the two switch tubes of the follow current clamping switch are connected to the midpoints of the direct-current input clamping capacitors of the inverter, in this way, the common-mode voltage of the inverter in the follow current stage is effectively clamped to be half of direct-current input voltage, the common-mode characteristic of the inverter is improved, then common-mode leak current of the photovoltaic inverter is eliminated, and personnel safety and device safety are guaranteed when the photovoltaic inverter is used.

Description

technical field [0001] The invention relates to the technical field of power electronic DC-AC conversion, in particular to a single-phase non-isolated photovoltaic inverter with a freewheeling clamp switch, which is suitable for photovoltaic power generation occasions. Background technique [0002] Photovoltaic grid-connected inverters require high efficiency, low cost, and can withstand the adverse effects of large output voltage fluctuations of photovoltaic cells, and their AC output must also meet high power quality. [0003] According to whether the inverter has an isolation transformer, it can be divided into isolation type and non-isolation type. The isolated photovoltaic inverter realizes the electrical isolation of the power grid and the battery panel, and ensures the safety of people and equipment, but it is bulky, expensive, and the system conversion efficiency is low. The non-isolated photovoltaic inverter structure does not contain a transformer, and has many ad...

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Problems solved by technology

However, the removal of the transformer leads to an electrical connection between the input and output. Due to the existence of the capacitance of the battery board to the ground, the common mode leakage current will be generated when the inverter is working, which will increase the electromagnetic interference of the system and affect the quality of the incoming current. Personal and Equipment Safety

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