Five-level neutral-point clamping type inverter topology with self-balance auxiliary bridge arm

Abstract

The inventiondiscloses a five-level neutral-point clamping type inverter topology with a self-balance auxiliary bridge arm, wherein the topology is mainly applied to the high-power wind power system and medium-high-voltage motor speed regulation fields as well as occasions of high-power active filtering and reactive compensation and the like. According to the topology, the main circuit comprises a direct-current bus capacitor, a self-balance flying capacitor auxiliary bridge arm, and a 5L-NPC inverter. With introduction of the self-balance flying capacitor auxiliary bridge arm, an inherent problem of potential unbalancing of the direct-current bus capacitor neutral point of the 5L-NPC inverter can be solved. According to the traditional auxiliary circuit, a controlled voltage source is used for generating a current at an electric reactor and thus the unbalanced current of the neutral point of the inverter can be offset, thereby realizing potential balancing. Unlike the traditional circuit, the provided self-balance auxiliary circuit uses the unbalancing current of the neutral point of the inverter to charge or discharge two flying capacitors and the voltages of the flying capacitors can be maintained to be constant; and the neutral-point potential balancing is realized automatically based on the capacitor clamping principle.

Description

technical field [0001] The invention relates to an inverter topology for realizing a complex medium-high-voltage high-power conversion system, in particular to a five-level mid-point clamp inverter topology with a self-balancing auxiliary bridge arm. Background technique [0002] In recent years, some new multi-level power converters have been widely used in the fields of medium and high voltage speed regulation, high voltage direct current transmission (HVDC), static Applications such as synchronous compensator (STATCOM) and power active filter (APF) have received extensive attention and become the preferred solution for medium and high voltage power conversion. However, the problem of unbalanced DC midpoint voltage generally exists in the multilevel clamp topology, and the balance of the DC bus voltage is a prerequisite for the normal operation of the entire multilevel power conversion system, so it is of great significance to carry out related research and analysis work ...

AI Technical Summary

Problems solved by technology

However, the unbalanced DC midpoint voltage generally exists in the multilevel clamp topology, and the balance of the DC bus voltage is a prerequisite for the normal operation of the entire multilevel power conversion system, so it is of great significance to carry out related research and analysis work very important

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