Publikationen (Hochschulbibliographie)

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Gui, Qiuye; Fehr, Hendrik; Gensior, Albrecht
Energy control of modular multilevel converters for drive applications at low frequency using general averaging. - In: IEEE transactions on power electronics, ISSN 1941-0107, Bd. 39 (2024), 5, S. 5239-5256

This article focuses on the energy control of modular multilevel converters (MMCs) for drive applications at low frequency. Utilizing the general averaging method, this work extends the results for MMC dc-operation in a previous work to low-frequency operation, and inherits all improvements with respect to model based controller design in dc-operation analysis, compared to other state-of-art approaches. The proposed energy control system - with either a constant or a stationary regime as reference for the instantaneous MMC energies - is proven to be globally stable, where the stability of the constant reference in low-frequency operation is confirmed theoretically, which is missing in state-of-art research. Besides, an optimization cooperating with two common-mode voltages for the energy control and compensation of ripples at low frequency is provided. The experiments verify the stability of the energy control system, and provide comparison between the two energy references in low-frequency operation for the first time, confirming the constant energy reference as a noteworthy option. The optimization improves the MMC performance, including the stationary operation generated by the optimization in cooperation with the approximated trapezoidal common-mode voltage as an improvement of a state-of-art solution in the sense of smaller arm currents RMS and cell capacitor voltage fluctuation.
Cai, Hui; Rädel, Uwe; Schlegel, Steffen; Westermann, Dirk
Integrated HiL simulation of multiple real-time simulator platforms to study the interactions in a multi-converters network. - In: IEEE Xplore digital library, ISSN 2473-2001, (2023), S. 1-5

With the increasing penetration of renewable energy sources, multi-converters networks are becoming more common. Therefore, understanding the interactions between these converters to ensure efficient and reliable power system operation becomes critical. We proposed an integrated hardware-in-the-loop (HiL) simulation approach using multiple real-time simulator platforms to study the interactions in a multiconverters network. Modeling converters with different depths is essential to investigate the effect of model complexity on the behavior of converters and their interactions in the network. In this paper, three modeling types of converters, namely the average-value model (AVM), the detailed equivalent model (DEM), and the emulated model (EM) are used to verify whether the research results derived in the low-depth model are equally applicable to the high-depth model. The results show that optimizing the converter parameters in one area of a distribution network in the AVM can optimize the oscillation behavior of the converters in another area. The conclusion can be applied to the other two high-depth models. This work highlights the importance of using multi-depth modeling approaches to investigate the interactions and optimization of converters in a multi-converters network.
Gui, Qiuye; Fehr, Hendrik; Gensior, Albrecht
Optimized stationary operating regime and common-mode voltage design for modular multilevel converters in drive applications at high frequency. - In: 2023 25th European Conference on Power Electronics and Applications (EPE'23 ECCE Europe), (2023), S. P.1-P.10

For modular multilevel converters in drive applications, a special low-frequency mode resulting in additional high current stress is generally utilized in the range around zero stator electrical frequency, since the conventional high-frequency mode for a higher frequency range may cause unaccepted large energy ripples in this low frequency range. To reduce the range for the undesired low-frequency mode, this paper aims on improving the high-frequency operation mode in terms of effectively reducing the cell capacitor voltage fluctuation, by means of a proposed online-implemented optimized stationary operating regime in cooperation with a new choice for the common-mode voltage which is designed under consideration of the energy ripples. Experiments confirm that the proposals lead to smaller cell capacitor voltage fluctuation than published variants, especially at relatively low frequencies.
Xie, Jun; Suberski, Martin; Henneberg, Dustin; Petzoldt, Jürgen; Li, Ying; Watson, Alan; De Novaes, Yales Romulo
A modified control strategy of neutral-point clamped converter-fed PMSM drives with engergy storage systems. - In: 2023 25th European Conference on Power Electronics and Applications (EPE'23 ECCE Europe), (2023), S. P.1-P.7

This paper proposes a modified control strategy for three-phase three-level neutral point clamped (NPC) converter-fed Permanent Magnet Synchronous Motor (PMSM) drive in the application of Energy Storage Systems (ESS) using single-carrier modulation. The increasing demands in renewable energy (RE) sources has attracts many research interests in recent years. The integration of different types of distributed DC systems has become a challenge for high power application. In this study, the NPC converter is employed for DC-AC conversion, with two ESS units serving as individual DC power supplies. The main focus is on simplification of the control and modulation technique for the NPC converter, which operates with individual ESS units having imbalanced SOC and voltages. The aim is to achieve balanced SOC between the ESS units and maintain high-quality AC output. Additionally, utilizing single-carrier modulation reduces the complexity of the control when a digital signal processor (DSP)-based platform is employed. Simulation results verifies effectiveness of the proposed method.
Fießer, Sven; Schwalbe, Ulf
Highly efficient and flexible optimization algorithm for magnetic components in power electronics with comprehensive thermal and power loss analysis. - In: 2023 25th European Conference on Power Electronics and Applications (EPE'23 ECCE Europe), (2023), S. P.1.-P.8

This paper presents an algorithm for the optimization of magnetic components in power electronics which includes a comprehensive analysis of the power losses and the temperature rise using dimensionless numbers for natural and forced convection. The results show that this approach is highly efficient and comparatively accurate.
Fehr, Hendrik; Gensior, Albrecht; Heidrich, Tobias; Möckel, Andreas
Comparison of two flywheel concepts for the support of microgrids. - In: 2023 25th European Conference on Power Electronics and Applications (EPE'23 ECCE Europe), (2023), S. P.1-P.8

Two flywheel storage concepts for microgrid integration are analyzed: fully-rated and split power conversion. The latter concept offers a cost reduction of the power electronic components. The results indicate an attractive tradeoff between converter cost and flywheel size at the same total effort for the electrical machines.
Xie, Jun; Suberski, Martin; Henneberg, Dustin; Rädel, Uwe; Petzoldt, Jürgen
A study on simplification of commutation methods for three-phase direct matrix converters. - In: 2023 25th European Conference on Power Electronics and Applications (EPE'23 ECCE Europe), (2023), S. P.1-P.7

This paper presents a simplified one-step commutation method for Direct Matrix Converter (DMC). A comprehensive study on commutation strategies of three-phase to three-phase DMC in a three-wire system is conducted, starting from the most commonly employed four-step commutation strategy. By considering the input voltages and the direction of the output currents, the commutation method can be simplified into three-step or two-step commutation methods. The input voltages are divided into six sectors. Through the constant holding of two switches within each sector, the proposed simplified one-step commutation method is achieved, which significantly contributes to the reduction of control complexity. The principle of the proposed strategy is explained in detail. Simulation results are used to verify effectiveness and performance of this proposed strategy.
Hartwig, Raphael;
Optimierter Multilevel-GaN-Umrichter für Niederspannungsindustrieanwendungen. - Ilmenau : Universitätsverlag Ilmenau, 2023. - 1 Online-Ressource (XXXI, 155 Seiten)
Technische Universität Ilmenau, Dissertation 2022

Das große Bauvolumen aktueller industrieller dreiphasiger Zweilevel-Netzumrichter und die damit verbundene geringe Leistungsdichte wird hauptsächlich durch den notwendigen EMV-Filter hervorgerufen. Aktuelle Veröffentlichungen zur Flying-Capacitor-Multilevel-Topologie zeigen das enorme Potential dieser Topologie im Hinblick auf kompakte EMV-Filter und eine damit verbundene hohe Leistungsdichte des gesamten Umrichters. Das Ergebnis dieser Arbeit zeigt, wie der Flying-Capacitor-Multilevel-Umrichter in Kombination mit GaN-Schaltern für Niederspannungsindustrie-anwendungen aussehen kann. Auf Basis der benötigten Komponenten eines solchen Umrichters wird zunächst eine Monte-Carlo Optimierung angefertigt. Die Ergebnisse dieser Optimierung zeigen einen Bereich für die elektrischen Parameter auf, in welchem eine größtmögliche Leistungsdichte und Effizienz für diesen Umrichter erzielt werden kann. Beruhend auf den Ergebnissen werden unterschiedlichste Hardwareprototypen, startend von der einzelnen Kommutierungszelle bis hin zum dreiphasigen Umrichter, vorgestellt. Untersuchungen an diesen Prototypen zeigen, dass es für die hohen resultierenden Schaltfrequenzen des dargestellten Umrichters noch einige unerforschte Effekte gibt. Diese beruhen zum Teil auf kleinsten parasitären Komponenten der Leiterplatte, oder der verwendeten Bauteile und können die Ausgangskennlinien des Umrichters stark beeinträchtigen. Mittels einer Simulation des Umrichters am Netz wird zudem validiert, dass ein solcher Umrichter mit einem dynamischen geschlossenen Regelkreis, wie er in Zweilevel-Umrichtern eingesetzt wird, betrieben werden kann. Überdies werden die typischen Betriebsbedingungen eines industriellen Umrichters theoretisch betrachtet, simuliert und validiert. Die Ergebnisse dieser Arbeit zeigen, dass die Topologie des Flying-Capacitor-Multilevel-Umrichters in Kombination mit GaN-Schaltern zu einer Verbesserung der Leistungsdichte, der Verluste und der Dynamik jeweils um Faktoren führen kann.
Hamouda, Noureddine; Babes, Badreddine; Kahla, Sami; Hamouda, Cherif; Rädel, Uwe
An optimized FO-PID controller and predictive current control of the APF connected AWPS for power quality improvement. - In: Przeglad elektrotechniczny, ISSN 0033-2097, Bd. 99 (2023), 5, S. 102-107

This paper deals with the design of a new topology of arc welding power supply (AWPS) based on an active power filter (APF) suitable to feed an arc welding machine. The principal task of this welding topology is to ensure a good welding process and ensure a unity power factor correction (PF), on the grid side, an active power filter (APF) is connected in parallel between the three-phase full bridge diode rectifier and the grid. The utility of the APF is to provide a unity power factor correction of arc welding power supply (AWPS). The predictive current control (PCC) and self-tuning filter (STF) are used to control the APF. On the arc welding machine side, an optimized FO-PID controller is used to control the welding current and voltage, by controlling the full bridge buck circuit, which offers many exceptional features, like a rapid response to load and grid voltage variations, and inherent short-circuit current limit which results in an improved welding performance and weld bead quality. the performance of the proposed configuration is examined in regards to its power quality given by reading the total harmonic distortion (THD) of the grid current is 3.47%, ensuring the best regulation of the DC-link voltage of APF, and providing a good tuning of the welding voltage and current. The parameters of the FO-PID controller are extracted by a Grey Wolf Optimization approach (GWO). Simulation results are noticed as satisfactory and prove the stability, accuracy, and dynamic response of the synthesized optimized regulating system.
Hamouda, Noureddine; Babes, Badreddine; Boutaghane, Amar; Gensior, Albrecht; Rädel, Uwe
Enhancing the width of molten pool and the tracking of welding current in gas metal arc welding processes using a robust PIλDμ controller. - In: Proceedings of the 2022 International Conference of Advanced Technology in Electronic and Electrical Engineering (ICATEEE), (2022), insges. 6 S.

With a high-speed welding power source based on better performance power electronic components and modern control methods, self-regulation of the electrode contact-tube to work-piece distance may be provided to offer With a high-speed welding power source based on better performance power electronic components and modern control methods, self-regulation of the electrode contact-tube to work-piece distance may be provided to offer additional features that can be fine-tuned to automate and improve the gas metal arc welding (GMAW) process. In this article, the dynamic properties of a self-regulated electrode to workpiece have been investigated when the length between the torch and the workpiece changes over time. The significant parts of arc welding processes have been analyzed and the suggested fractional PID (PI λ D μ ) regulator has been created to keep the welding current during the fusing and short-circuiting of electric wires within a specified range. In this study, the most effective FOPID regulator parameters is designed with a weighted sum multi-objective optimization technique using the Bacterial Foraging Optimization (BFO) technique with weights associated with various criteria including Integral Absolute Error (IAE), Integral Time Absolute Error (ITAE), Integral Time Square Error (ITSE), and Integral Square Error (ISE). Numerical simulations using MATLAB/SIMULINK are conducted to indicate the usefulness of the proposed P Iλ D μ controller over conventional PID controller and knowledge of the processes, which adjust the welding voltage and arc current in reaction to variations in arc length. The simulation results show that this automatic arc welding control system can perform effectively.