Investigation of capacitor voltage balancing in practical implementations of flying capacitor multilevel converters

Reported capacitor average natural voltage balancing dynamics analysis methods are mostly based on frequencydomain Fourier transformations that involve infinite series. Therefore, these methods require high mathematical skills, are not truly analytical and difficult to use in engineering practise. This study suggests a time-domain power averaging-based approach to the analysis of a multilevel DC-DC flying capacitor converter (or, more generally, switched capacitive converter) aperiodic (non-oscillating) average voltage balancing dynamics. Simple analytical solutions are illustrated by single and dual capacitor converter examples that include pure resistive load and balance booster circuit. Theoretical results are supported by simulations and experimental verification.

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“…Normalised graphs of (19) and (20) are shown in Fig. 9 with the maximum decay factor (D = 0.5) being [12]…”

Section: Derivation Of Averaged Differential Equations For Switched Rmentioning

confidence: 99%

“…Most recent FC converter-related papers [20][21][22] address capacitor voltage imbalance and possible active balancing control strategies for different converter topologies. In [22], FC voltage imbalance (asymmetry) is introduced on purpose in order to increase the number of output levels for the same number of semiconductors.…”

Section: Introductionmentioning

confidence: 99%

Simple time‐domain analysis of a multilevel DC–DC flying capacitor converter average aperiodic natural balancing dynamics

Penczek

Mondzik

Stala

et al. 2019

IET Power Electronics

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“…While FCML converters exhibit natural balancing that guarantees the initial capacitor voltage imbalances will eventually decay, it is challenging to analytically predict how long the process takes. Moreover, natural balancing cannot correct for periodic disturbances that result in large capacitor voltage imbalances at steady-state [8]. This paper investigates voltage balancing of flying capacitors in the multiphase FCML converter with coupled inductors.…”

Section: Introductionmentioning

confidence: 99%

Voltage Balancing of Multiphase FCML Converters with Coupled Inductors

Zhou¹,

Chen²

2021

Preprint

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<div>Flying capacitor voltage balancing is critical for the performance of flying capacitor multilevel (FCML) converters. This paper investigates the intrinsic capacitor voltage balancing of multiphase FCML converters with coupled inductors. It is shown that the coupled inductor provides flying capacitor voltage balancing that minimizes steady-state imbalances due to periodic disturbances compared to converters with uncoupled inductors. A dynamic model of natural balancing of the converter is derived and used to estimate the time required for the flying capacitors to settle from an initial imbalance. The theoretical predictions are verified with analytical derivations, SPICE simulations, and experimental results.</div>

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“…The most extensive drawback of this type of inverter is the FCs voltages balancing control which can impact the quality of the output waveform [6, 7]. Several voltage balancing strategies have been presented in the literature [20–28]. These methods offer the ability to regulate the voltage across the FCs which use the redundant state selection (RSS), add auxiliary voltages, and modify the duty cycles.…”

Section: Introductionmentioning

confidence: 99%

“…This method needs the measurement of the voltage across each FC which leads to using extra hardware. In [24–27], authors present a control scheme for FCMI based on manipulating the phase‐shifted sinusoidal pulse‐width modulation in order to regulate directly the flying‐capacitor voltages. This method is based on the addition of a small square waveform to the typical modulation signals.…”

Section: Introductionmentioning

confidence: 99%

Hybrid four‐level FC inverter using an internal supercapacitor storage system for a microgrid connected application

Mansouri

Tnani

Bachelier

2020

IET power electron.

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In this study, a new topology of grid‐connected four‐level inverter is introduced. The proposed structure, based on intermediate supercapacitors energy storage, is introduced to ensure two operation modes: to provide power to a microgrid from renewable energy sources and to regulate its voltage during short‐term power disturbances. The main idea is to replace ordinary capacitors of a four‐level flying capacitor (FC) inverter by supercapacitors and operate them under variable voltage conditions. The control strategy applies linear matrix inequalities approach as well as space vector modulation technique to generate the appropriate switching states. The latter part of this study is dedicated to the redundant state selection method for supercapacitors voltages balancing. Through experimental implementation, presented results highlight the efficiency of the proposed hybrid inverter in ensuring microgrid stability.

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Investigation of capacitor voltage balancing in practical implementations of flying capacitor multilevel converters

Cited by 61 publications

References 15 publications

Simple time‐domain analysis of a multilevel DC–DC flying capacitor converter average aperiodic natural balancing dynamics

Simple time‐domain analysis of a multilevel DC–DC flying capacitor converter average aperiodic natural balancing dynamics

Voltage Balancing of Multiphase FCML Converters with Coupled Inductors

Hybrid four‐level FC inverter using an internal supercapacitor storage system for a microgrid connected application

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