A Voltage Balancing Method for Uncontrolled Pre-Charging in Modular Multilevel Converters

Abstract

Ensuring balanced voltage distribution across submodule capacitors remains a critical challenge in modular multilevel converters. This paper identifies a significant stability issue: when integrated circuits on power submodules draw power directly from their respective submodule capacitors, it leads to uneven charging patterns and voltage instability. After analyzing the system stability conditions, this paper proposes a novel hardware-based pre-charging method that achieves uniform voltage distribution across all submodule capacitors. This solution effectively addresses this practical engineering challenge, enabling more reliable modular multilevel converter operation in high-power applications.

Authors 1

1. Rik W. De Doncker Aachen Research Campus Flexible Electrical Networks Institute of Power Generation and Storage Systems

   RWTH Aachen University

   Affiliation as printed

   Research Campus Flexible Electrical Networks, Institute of Power Generation and Storage Systems, RWTH Aachen University,Aachen,Germany