A Five-Level Neutral Point Clamped Inverter Topology with Self-Balanced Auxiliary Legs

Abstract

The invention discloses a five-level midpoint clamp inverter topology with a self-balancing auxiliary bridge arm, which is mainly used in high-power wind power systems, medium and high-voltage motor speed regulation fields, and high-power active filtering and reactive power compensation. and other occasions. The main circuit of this topology includes DC bus capacitor, self-balancing flying capacitor auxiliary bridge arm and 5L‑NPC inverter. The introduction of the flying capacitor auxiliary bridge arm is mainly used to solve the potential imbalance problem at the midpoint of the DC bus capacitor inherent in the 5L-NPC inverter. The traditional auxiliary circuit uses a controlled voltage source to generate current on a reactor to offset the unbalanced current at the midpoint of the inverter, thereby achieving potential balance. Different from this, the self-balancing auxiliary circuit proposed by the present invention uses the unbalanced current at the midpoint of the inverter to charge and discharge the two flying capacitors, and keeps the voltage of the flying capacitors constant, and then uses the capacitor clamping principle to automatically realize The balance of the midpoint potential.

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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