A five-level inverter

Abstract

The invention provides a five-level inverter, which includes six switch tubes, two inductors, four capacitor units and two anti-backflow devices. Wherein, the common terminal of the third capacitor unit and the fourth capacitor unit is connected to the common terminal of the first capacitor unit and the second capacitor unit. The third capacitor unit and the fourth capacitor unit are the output filter circuits of the inverter, and the common terminal of the third capacitor unit and the fourth capacitor unit is the midpoint of the DC bus. It can be seen that in the inverter of the present invention, the potential of the midpoint of the DC bus (or the positive or negative pole of the DC power supply) relative to the midpoint of the output filter circuit is relatively stable, and the positive or negative pole of the DC bus will not appear power frequency relative to the ground. Or high-frequency jump voltage, so there will be no leakage current problem. In addition, the five-level output has high efficiency and is suitable for applications such as photovoltaic power generation.

Description

technical field [0001] The invention relates to the technical field of power electronics, in particular to a five-level inverter. Background technique [0002] The inverter is used to convert the DC voltage output by the DC power supply into an AC voltage and then output it to the load circuit. It is widely used in photovoltaic, wind power generation and other fields. However, due to the existence of the parasitic capacitance of the DC power supply (such as a solar panel) to the ground, there may be a problem of leakage current when the inverter is working. The leakage current problem will not only damage the output power quality and reduce the working efficiency of the inverter, but also cause harm to the human body and reduce the reliability of the inverter. [0003] At present, in order to solve the problem of leakage current, inverters with topologies such as H5, H6, and HERIC have appeared, but these inverters are all three-level inverters, so the efficiency is low. C...

AI Technical Summary

Problems solved by technology

E.g, figure 1 It is an existing five-level inverter. When the inverter is working, the DC positive pole of the DC power supply is relative to the output negative pole, that is, there will be a power frequency jump at point C, and the power frequency jump voltage acts on the DC The parasitic capacitance between the positive pole (or negative pole) of the power supply DC and the ground will cause leakage current spikes

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