Capacitor Voltage Balancing of a Grid-Tied, Cascaded Multilevel Converter with Binary Asymmetric Voltage Levels Using an Optimal One-Step-Ahead Switching-State Combination Approach
Artikel i vetenskaplig tidskrift, 2022

This paper presents a novel capacitor voltage balancing control approach for cascaded multilevel inverters with an arbitrary number of series-connected H-Bridge modules (floating capacitor modules) with asymmetric voltages, tiered by a factor of two (binary asymmetric). Using a nearest-level reference waveform, the balancing approach uses a one-step-ahead approach to find the optimal switching-state combination among all redundant switching-state combinations to balance the capacitor voltages as quickly as possible. Moreover, using a Lyapunov function candidate and considering LaSalle's invariance principle, it is shown that an offline calculated trajectory of optimal switching-state combinations for each discrete output voltage level can be used to operate (asymptotically stable) the inverter without measuring any of the capacitor voltages, achieving a novel sensorless control as well. To verify the stability of the one-step-ahead balancing approach and its sensorless variant, a demonstrator inverter with 33 levels is operated in grid-tied mode. For the chosen 33-level converter, the NPC main-stage and the individual H-bridge modules are operated with an individual switching frequency of about 1 kHz and 2 kHz, respectively. The sensorless approach slightly reduced the dynamic system response and, furthermore, the current THD for the chosen operating point was increased from 3.28% to 4.58% in comparison with that of using the capacitor voltage feedback.

Modular multilevel converters

Sensorless control

Multilevel systems

Total harmonic distortion

Power supplies


Manuel Kuder

Universität Der Bundeswehr München

Anton Kersten

Universität Der Bundeswehr München

Chalmers, Elektroteknik, Elkraftteknik

Jose Luis Marques-Lopez

Universität Der Bundeswehr München

Julian Estaller

Universität Der Bundeswehr München

Johannes Buberger

Universität Der Bundeswehr München

Florian Schwitzgebel

Universität Der Bundeswehr München

Torbjörn Thiringer

Chalmers, Elektroteknik, Elkraftteknik

Anton Lesnicar

Universität Der Bundeswehr München

Rainer Marquardt

Universität Der Bundeswehr München

Thomas Weyh

Universität Der Bundeswehr München

Richard Eckerle

Universität Der Bundeswehr München


1996-1073 (ISSN)

Vol. 15 2 575



Annan elektroteknik och elektronik



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