Four-level topological unit and application circuit thereof

Abstract

The invention relates to a four-level topological unit which is connected between a positive plate and a negative plate of a direct-current power supply and comprises a first switch unit, a second switch unit, a third switch unit, a fourth switch unit, a fifth switch unit, a sixth switch unit, a seventh switch unit, an eighth switch unit, diodes which are reversely connected to the two ends of each switch unit respectively, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor and a current limiting inductor. The four-level topological unit can provide higher alternating-current voltage under the condition of keeping low loss, can prevent overvoltage of the two ends of a flying capacitor and a part of switch tubes or diodes at the same time, can effectively reduce the cost and the loss of the alternating-current side of an AC / DC converter and is higher in reliability. The invention also discloses an application circuit of the four-level topological unit.

Description

technical field [0001] The invention relates to the technical field of power electronics, in particular to a four-level topology unit and an application circuit thereof. Background technique [0002] A bidirectional AC-DC converter is a converter that converts DC power into AC power or converts AC power into DC power. With the continuous development and progress of society, human beings' demand for energy is increasing day by day, and new energy sources such as photovoltaics and energy storage account for an increasing proportion of energy. As its core, photovoltaic inverters and energy storage converters have become more and more fierce in the market competition in recent years. In order to meet the market demand, more and more multi-level AC-DC converters are introduced into the market, such as four-level AC-DC converters. [0003] In traditional four-level AC-DC converters, voltage equalization measures and larger snubber circuits are required to prevent overvoltage acr...

AI Technical Summary

Problems solved by technology

[0004] Based on this, it is necessary to adopt voltage equalization measures and larger snubber circuits in traditional four-level AC-DC converters to prevent overvoltage at both ends of flying capacitors, some switches and diodes, and traditional four-level AC-DC converters The topological packaging structure in the device is not universal. In practical applications, it is generally necessary to repackage it, which will bring about the problems of increased cost and poor reliability. A four-level topological unit and its application circuit are provided.

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