Modeling, Analysis, and Control of Circulating Currents in Half-bridge Modular Multilevel Converters PDF Download

Author: Cesar Gabiel Marzoa Montalvo
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Book Description
In operating Modular Multilevel Converters (MMCs) the common practice is to eliminate circulating currents using a Circulating Current Suppression Controller (CCSC). This practice reduces converter losses and submodule capacitor voltage ripple; it also allows usage of semiconductors with lower ratings. Although preliminary research has pointed to the possibility of minimizing capacitor voltage ripple or converter losses by injecting circulating currents, little formal analysis has been conducted on how the improvement of one will affect the other, or on how to control the ripple or the losses. This thesis presents a detailed analysis on how to inject a precise amount of circulating currents in order to obtain certain submodule capacitor ripple. A mathematical model that describes the capacitor voltage ripple based on the second-order circulating current contents is used to determine the ripple profile of the converter at a given operating point. Then it is possible to determine what amount of circulating current needs to be injected to obtain a certain ripple. An analysis of how such circulating current injection affects losses is also made. The proposed method is validated using PSCAD/EMTDC simulations, where a high level of accuracy is observed. Validation using a Real-Time Digital Simulator (RTDS) using a Control Hardware-in-Loop (CHIL) scheme is also presented. An implementation in a down-scaled MMC prototype further validates the proposed method. This thesis shows that the optimal operating point (regarding losses and capacitor voltage ripple) for MMCs is not achieved by using a conventional CCSC, as is the common practice today; instead injecting a certain amount of second-order circulating current can reduce both ripple and converter losses simultaneously.

Author: Sixing Du
Publisher: John Wiley & Sons
ISBN: 1119366305
Category : Science
Languages : en
Pages : 360

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Book Description
An invaluable academic reference for the area of high-power converters, covering all the latest developments in the field High-power multilevel converters are well known in industry and academia as one of the preferred choices for efficient power conversion. Over the past decade, several power converters have been developed and commercialized in the form of standard and customized products that power a wide range of industrial applications. Currently, the modular multilevel converter is a fast-growing technology and has received wide acceptance from both industry and academia. Providing adequate technical background for graduate- and undergraduate-level teaching, this book includes a comprehensive analysis of the conventional and advanced modular multilevel converters employed in motor drives, HVDC systems, and power quality improvement. Modular Multilevel Converters: Analysis, Control, and Applications provides an overview of high-power converters, reference frame theory, classical control methods, pulse width modulation schemes, advanced model predictive control methods, modeling of ac drives, advanced drive control schemes, modeling and control of HVDC systems, active and reactive power control, power quality problems, reactive power, harmonics and unbalance compensation, modeling and control of static synchronous compensators (STATCOM) and unified power quality compensators. Furthermore, this book: Explores technical challenges, modeling, and control of various modular multilevel converters in a wide range of applications such as transformer and transformerless motor drives, high voltage direct current transmission systems, and power quality improvement Reflects the latest developments in high-power converters in medium-voltage motor drive systems Offers design guidance with tables, charts graphs, and MATLAB simulations Modular Multilevel Converters: Analysis, Control, and Applications is a valuable reference book for academic researchers, practicing engineers, and other professionals in the field of high power converters. It also serves well as a textbook for graduate-level students.

Author: Aleksandr Viatkin
Publisher: Springer Nature
ISBN: 3031247124
Category : Technology & Engineering
Languages : en
Pages : 158

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Book Description
This book reports on a comprehensive study on a novel high-power converter, i.e. a Modular Multilevel Converter with Interleaved Half-bridge Submodules (ISM-MMC). It describes in depth its average model, the operating principles, as well as a new control method and a hybrid modulation strategy that help to exploit the benefits of the interleaving scheme. The new power converter is particularly advantageous for high-current applications that require superb quality of input/output waveforms. Moreover, this book reports on a systematic study of the current balancing problem between parallel-connected units that commutate in non-simultaneous fashion. This is a typical issue in interleaved converters, however here it is analyzed for the first time in relation to MMC-based structures. Two control strategies are proposed to cope with this matter. By using a sensorless regulation scheme, the number of required current transducers has been minimized, reducing complexity, cost, and footprint of the hardware, while providing converter with a fast and accurate current balancing. This book also offers a comprehensive comparison between several practical designs of ISM-MMC and classical MMC for an ultra-fast electrical vehicle charger. All in all, it provides graduate students and researchers, as well as field engineers and professionals with extensive information and essential practical details on the state-of-the-art MMC and ISM-MMC design.

Author: Fujin Deng
Publisher: John Wiley & Sons
ISBN: 1119875625
Category : Technology & Engineering
Languages : en
Pages : 372

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Book Description
Modular Multilevel Converters Expert discussions of cutting-edge methods used in MMC control, protection, and fault detection In Modular Multilevel Converters: Control, Fault Detection, and Protection, a team of distinguished researchers delivers a comprehensive discussion of fault detection, protection, and tolerant control of modular multilevel converters (MMCs) under internal and external faults. Beginning with a description of the configuration of MMCs, their operation principles, modulation schemes, mathematical models, and component design, the authors go on to explore output control, fault detection, capacitor monitoring, and other topics of central importance in the field. The book offers summaries of centralized capacitor voltage-balancing control methods and presents several capacitor monitoring methods, like the direct and sorting-based techniques. It also describes full-bridge and half-bridge submodule-based hybrid MMC protection methods and alternative fault blocking SM-based MMCs. Readers will also find: A thorough introduction to modular multilevel converters, including circuits, operation principles, modulation, mathematical models, components, and design constraints In-depth discussions of the control of modular multilevel converters, including output control, centralized capacitor voltage control, and individual capacitor voltage control Comprehensive explorations of fault detection of MMCs under IGBT faults, including short-circuit and open-circuit faults, as well as fault-tolerant control of MMCs Fulsome treatments of the control of MMCs under AC grid faults, including discussions of AC-side current control Perfect for electrical engineering researchers, Modular Multilevel Converters: Control, Fault Detection, and Protection, will also earn a place in the libraries of electrical engineers working in industry, as well as undergraduate and graduate students with an interest in MMCs.

Author: Kamran Sharifabadi
Publisher: John Wiley & Sons
ISBN: 1118851544
Category : Science
Languages : en
Pages : 522

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Book Description
Design, Control and Application of Modular Multilevel Converters for HVDC Transmission Systems is a comprehensive guide to semiconductor technologies applicable for MMC design, component sizing control, modulation, and application of the MMC technology for HVDC transmission. Separated into three distinct parts, the first offers an overview of MMC technology, including information on converter component sizing, Control and Communication, Protection and Fault Management, and Generic Modelling and Simulation. The second covers the applications of MMC in offshore WPP, including planning, technical and economic requirements and optimization options, fault management, dynamic and transient stability. Finally, the third chapter explores the applications of MMC in HVDC transmission and Multi Terminal configurations, including Supergrids. Key features: Unique coverage of the offshore application and optimization of MMC-HVDC schemes for the export of offshore wind energy to the mainland. Comprehensive explanation of MMC application in HVDC and MTDC transmission technology. Detailed description of MMC components, control and modulation, different modeling approaches, converter dynamics under steady-state and fault contingencies including application and housing of MMC in HVDC schemes for onshore and offshore. Analysis of DC fault detection and protection technologies, system studies required for the integration of HVDC terminals to offshore wind power plants, and commissioning procedures for onshore and offshore HVDC terminals. A set of self-explanatory simulation models for HVDC test cases is available to download from the companion website. This book provides essential reading for graduate students and researchers, as well as field engineers and professionals who require an in-depth understanding of MMC technology.

Author: Baljit Singh Riar
Publisher:
ISBN:
Category : Electric current converters
Languages : en
Pages : 147

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Book Description
An increasing awareness of energy efficiency has led to the development of several improved semiconductor devices, power converter topologies and control schemes within the field of power electronics. Recent advances in multilevel converters, especially Modular Multilevel Converters (M2LCs), have improved upon existing power conversion technology in several aspects, including efficiency, power quality, modularity and reliability. There are, however, several challenges associated with the M2LC topology, which include capacitor voltage variations, voltage balancing, circulating currents and increased complexity of the overall control scheme. This thesis contributes to the ongoing research on the M2LC topology by proposing the following solutions to the aforementioned challenges. Typically, schemes with cascaded control loops have been used to control M2LCs and these schemes could affect the performance of the converter. Model Predictive Direct Current Control (MPDCC), which has a single loop, is proposed to keep load currents within tight bounds, while minimising both capacitor voltage variations and circulating currents. Moreover, the width of the current bounds sets the level of Total Harmonic Distortion (THD) of the currents. Simulated and experimental results for a 860-VA prototype M2LC are presented to demonstrate the effectiveness of the MPDCC scheme. A modified M2LC topology that employs a full-bridge module in each arm is proposed to minimise both circulating currents and capacitor voltage variations. The modified topology allows for decoupled control of the load and circulating currents, where the load and circulating currents are controlled by the half-bridge and full-bridge modules, respectively. A comparative investigation with respect to a conventional topology, using theoretical as well as experimental results for a 800-VA prototype converter, reveals that the modified topology offers superior performance. Capacitor voltage variations are difficult to control within the conventional M2LC, because the variations are coupled to arm currents and load currents. An alternative M2LC topology that uses Inductive Power Transfer (IPT) technology is proposed to simplify the control of the capacitor voltages. The IPT system keeps the voltage variations within bounds irrespective of the operating conditions of the converter. The feasibility of the concept and improvements achieved with the alternative topology are demonstrated using simulations of a 800-VA converter.

Author: Davide del Giudice
Publisher: Springer Nature
ISBN: 3031128184
Category : Technology & Engineering
Languages : en
Pages : 126

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Book Description
This book provides a comprehensive review of the models and approaches that can be employed to simulate modular multilevel converters (MMCs). Each solution is described in terms of operating principle, fields of applicability, advantages, and limitations. In addition, this work proposes a novel and efficient simulation approach for MMCs based on sub-circuit isomorphism. This technique, which has its roots in the electronics fields, can be profitably exploited to simulate MMCs regardless of the model used to describe its sub-modules, including the most accurate ones. Lastly, this book considers a well-known high voltage direct current (HVDC) benchmark system consisting of two MMCs. After describing the implementation details of each benchmark component, simulation results in several scenarios (ranging from normal operating conditions to faults in the AC and DC grid) are included to validate the proposed approach and showcase its key features. Due to its educational content, this book constitutes a useful guide for PhD students and researchers interested in the topic of MMCs and their simulation. It also serves as a starting platform for junior electrical engineers who work in the field of power electronic converters for HVDC systems.

Author: Su Zhang
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Book Description
The investigation of improved semiconductor devices, power converter topologies and modulation schemes is essential for the development of advanced power electronics technology. As a preferred option of power conversion for high-power applications, multilevel converters, especially Modular Multilevel Converters (MMCs), are gaining increasing popularity in both industry and academia. However, there are several technical challenges associated with the MMC topology. One of the main challenges is the minimization of voltage variations in module capacitors. In addition, the circulating currents, which originate from both the capacitor voltage variations and switching scheme, increase the rating of power devices and power losses. Typically, cascaded control schemes, based on Proportional-Integral (PI) controllers and Pulse Width Modulators (PWMs), have predominately been used to control MMCs. However, tuning of multiple PI loops is difficult and also influences the performance of MMC at both steady-state and transient operating conditions. To overcome these drawbacks, this thesis proposes a Model Predictive Direct Slope Control (MPDSC) scheme for MMCs. This scheme is capable of handling multiple control objectives without using a modulator, thus significantly simplifies the complexity of the control scheme. In addition, a long prediction horizon can be generated without increasing the computational burden of the control algorithm, and therefore the performance of the MMC could be further improved with a shorter sampling time. The viability of MPDSC is demonstrated using simulated and experimental results of a 380-VA prototype MMC, as well as benchmarking against the performance of a prototype controlled by Model Predictive Direct Current Control (MPDCC) scheme. The MPDSC offers performance that is comparable to MPDCC, but with significantly reduced complexity and computational burden. However, this scheme considers all possible switching states to evaluate each control variable, this invariably making the computational burden still heavy. In addition to this, the tuning of multiple weighting factors is cumbersome and inefficient. To overcome these drawbacks, this thesis proposes a Hierarchical Model Predictive Control (HMPC) scheme for MMCs. With this scheme, the load currents are regulated within symmetrical bounds using a modified MPDSC, and the capacitor voltages, circulating currents and switching frequency are minimized through a Model Predictive Multilayer Control (MPMC) scheme. To reduce computational burden of the control algorithm, HMPC evaluates each control variable independently while minimizing the number of switching states for evaluation. Instead of using conventional weighting factors, HMPC utilizes the number of switching states of lower costs as a tuning factor for each control variable, which makes the tuning process efficient and adaptable to any operating conditions. A comparison with a conventional Finite Control Set Model Predictive Control (FCS-MPC) scheme, using simulated as well as experimental results of a prototype MMC, reveals that HMPC offers superior performance. With MPDSC and HMPC schemes, the capacitor voltage variations of MMCs can only be reduced to a certain level. Therefore, this thesis presents a modified MMC topology that utilizes an Inductive Power Transfer (IPT) system to maintain the capacitor voltages within tight bounds. This topology simplifies the control of capacitor voltages, irrespective of the switching scheme and operating conditions of the converter. A mathematical model of the modified topology is developed, and a control scheme is also proposed. The feasibility of the control scheme and the accuracy of the mathematical model are validated using simulated as well as theoretical results of a 2-kVA MMC-IPT system.

Author: Gabriele Grandi
Publisher: MDPI
ISBN: 3039214810
Category : Technology & Engineering
Languages : en
Pages : 548

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Book Description
This book is a collection of scientific papers concerning multilevel inverters examined from different points of view. Many applications are considered, such as renewable energy interface, power conditioning systems, electric drives, and chargers for electric vehicles. Different topologies have been examined in both new configurations and well-established structures, introducing novel and particular modulation strategies, and examining the effect of modulation techniques on voltage and current harmonics and the total harmonic distortion.

Author: Julie A. Bannantine
Publisher: Pearson
ISBN:
Category : Business & Economics
Languages : en
Pages : 296

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Book Description
The first book to present current methods and techniques of fatigue analysis, with a focus on developing basic skills for selecting appropriate analytical techniques. Contains numerous worked examples, chapter summaries, and problems. (vs. Fuchs/Stevens).