Non-isolated five-level inverter and leakage current boycotting strategy thereof

Abstract

The invention provides a non-isolated five-level inverter and a leakage current boycotting strategy thereof. The non-isolated five-level inverter comprises a first bridge arm, a second bridge arm, a first follow current loop and a second follow current loop, the first bridge arm is parallelly connected with a battery, the second bridge arm is parallelly connected with the battery, the first followcurrent loop is connected with the first bridge arm and the second bridge arm, the second follow current loop is connected with the first bridge arm and the second bridge arm, parts of switch devicesin the first bridge arm, the second bridge arm, and a formed current path can keep common-mode voltage of the non-isolated five-level inverter constant after the first follow current loop and / or thesecond follow current loop are conducted at the follow current stage. According to a five-level topological structure and the leakage current boycotting strategy, the problem of balance of clamping capacitor voltage can be solved, the charging time and the discharging time of a clamping capacitor are equal within an on-off period, so that the constant value of the common-mode voltage of the non-isolated five-level inverter is ensured.

Description

technical field [0001] The invention relates to the field of control technology, in particular to a non-isolated five-level inverter and a leakage current suppression strategy thereof. Background technique [0002] At present, in the photovoltaic grid-connected system, the photovoltaic inverter plays an important role in the process of electric energy conversion. As an important interface between photovoltaic cells and the grid, photovoltaic grid-connected inverters can be divided into isolated inverters and non-isolated inverters according to whether the inverter system contains an isolation transformer. In an isolated inverter system, a high-frequency transformer is usually installed on the DC side or a low-frequency transformer is installed on the low-frequency side. The transformer not only boosts the DC voltage of the photovoltaic cell, but also isolates the DC side and the AC side, so that there is no DC loop between the two. However, the existence of the transformer...

AI Technical Summary

Problems solved by technology

The main disadvantage of the Heric topology is that there are too many switches, thus requiring a more complex converter

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