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  Subjects -> ELECTRONICS (Total: 138 journals)
Advances in Biosensors and Bioelectronics     Open Access   (Followers: 2)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 5)
Advances in Microelectronic Engineering     Open Access   (Followers: 1)
Advances in Power Electronics     Open Access   (Followers: 7)
Aerospace and Electronic Systems, IEEE Transactions on     Hybrid Journal   (Followers: 54)
American Journal of Electrical and Electronic Engineering     Open Access   (Followers: 7)
Annals of Telecommunications     Hybrid Journal   (Followers: 4)
APL : Organic Electronics and Photonics     Hybrid Journal   (Followers: 1)
APSIPA Transactions on Signal and Information Processing     Open Access   (Followers: 3)
Archives of Electrical Engineering     Open Access   (Followers: 9)
Autonomous Mental Development, IEEE Transactions on     Hybrid Journal   (Followers: 5)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 8)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 14)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 12)
Biomedical Instrumentation & Technology     Full-text available via subscription   (Followers: 4)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 5)
BULLETIN of National Technical University of Ukraine. Series RADIOTECHNIQUE. RADIOAPPARATUS BUILDING     Open Access   (Followers: 1)
Bulletin of the Polish Academy of Sciences : Technical Sciences     Open Access  
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 13)
China Communications     Full-text available via subscription   (Followers: 1)
Circuits and Systems     Open Access   (Followers: 7)
Consumer Electronics Times     Open Access   (Followers: 3)
Control Systems     Hybrid Journal   (Followers: 19)
Electronic Markets     Hybrid Journal   (Followers: 5)
Electronic Materials Letters     Hybrid Journal   (Followers: 2)
Electronics     Open Access   (Followers: 5)
Electronics and Communications in Japan     Hybrid Journal   (Followers: 4)
Electronics Letters     Hybrid Journal   (Followers: 15)
Embedded Systems Letters, IEEE     Hybrid Journal   (Followers: 14)
EPJ Quantum Technology     Open Access  
EURASIP Journal on Embedded Systems     Open Access   (Followers: 8)
Foundations and TrendsĀ® in Communications and Information Theory     Full-text available via subscription   (Followers: 6)
Foundations and TrendsĀ® in Signal Processing     Full-text available via subscription   (Followers: 4)
Frequenz     Full-text available via subscription   (Followers: 1)
Frontiers of Optoelectronics     Hybrid Journal   (Followers: 1)
Geoscience and Remote Sensing, IEEE Transactions on     Hybrid Journal   (Followers: 19)
Haptics, IEEE Transactions on     Hybrid Journal   (Followers: 4)
IEEE Consumer Electronics Magazine     Full-text available via subscription   (Followers: 7)
IEEE Journal of Emerging and Selected Topics in Power Electronics     Hybrid Journal   (Followers: 4)
IEEE Journal of the Electron Devices Society     Open Access   (Followers: 1)
IEEE Power Electronics Magazine     Full-text available via subscription   (Followers: 1)
IEEE Transactions on Audio, Speech, and Language Processing     Hybrid Journal   (Followers: 9)
IEEE Transactions on Automatic Control     Hybrid Journal   (Followers: 20)
IEEE Transactions on Consumer Electronics     Hybrid Journal   (Followers: 11)
IEEE Transactions on Electron Devices     Hybrid Journal   (Followers: 6)
IEEE Transactions on Information Theory     Hybrid Journal   (Followers: 13)
IEEE Transactions on Power Electronics     Hybrid Journal   (Followers: 13)
IEICE - Transactions on Electronics     Full-text available via subscription   (Followers: 8)
IEICE - Transactions on Information and Systems     Full-text available via subscription   (Followers: 7)
IET Power Electronics     Hybrid Journal   (Followers: 7)
IET Wireless Sensor Systems     Hybrid Journal   (Followers: 5)
IETE Journal of Education     Open Access   (Followers: 2)
IETE Journal of Research     Open Access   (Followers: 5)
IETE Technical Review     Open Access   (Followers: 1)
Industrial Electronics, IEEE Transactions on     Hybrid Journal   (Followers: 10)
Industry Applications, IEEE Transactions on     Hybrid Journal   (Followers: 5)
Informatik-Spektrum     Hybrid Journal  
Instabilities in Silicon Devices     Full-text available via subscription  
Intelligent Transportation Systems Magazine, IEEE     Full-text available via subscription   (Followers: 1)
International Journal of Advanced Electronics and Communication Systems     Open Access   (Followers: 4)
International Journal of Advanced Research in Computer Science and Electronics Engineering     Open Access   (Followers: 18)
International Journal of Advances in Telecommunications, Electrotechnics, Signals and Systems     Open Access   (Followers: 1)
International Journal of Aerospace Innovations     Full-text available via subscription   (Followers: 11)
International Journal of Applied Electronics in Physics & Robotics     Open Access   (Followers: 1)
International Journal of Biomedical Nanoscience and Nanotechnology     Hybrid Journal   (Followers: 5)
International Journal of Computational Vision and Robotics     Hybrid Journal   (Followers: 4)
International Journal of Computer & Electronics Research     Full-text available via subscription   (Followers: 2)
International Journal of Control     Hybrid Journal   (Followers: 11)
International Journal of Electronics     Hybrid Journal   (Followers: 2)
International Journal of Electronics & Data Communication     Open Access   (Followers: 3)
International Journal of Electronics and Telecommunications     Open Access   (Followers: 3)
International Journal of Granular Computing, Rough Sets and Intelligent Systems     Hybrid Journal   (Followers: 1)
International Journal of High Speed Electronics and Systems     Hybrid Journal  
International Journal of Microwave and Wireless Technologies     Hybrid Journal   (Followers: 1)
International Journal of Nano Devices, Sensors and Systems     Open Access   (Followers: 1)
International Journal of Nanoscience     Hybrid Journal   (Followers: 1)
International Journal of Numerical Modelling:Electronic Networks, Devices and Fields     Hybrid Journal   (Followers: 2)
International Journal of Power Electronics     Hybrid Journal   (Followers: 3)
International Journal of Review in Electronics & Communication Engineering     Open Access   (Followers: 1)
International Journal of Sensors, Wireless Communications and Control     Hybrid Journal   (Followers: 2)
International Journal of Systems, Control and Communications     Hybrid Journal   (Followers: 2)
International Journal on Communication     Full-text available via subscription   (Followers: 7)
International Journal on Electrical and Power Engineering     Full-text available via subscription   (Followers: 10)
ISRN Electronics     Open Access   (Followers: 1)
ISRN Signal Processing     Open Access  
Journal of Advanced Dielectrics     Open Access   (Followers: 1)
Journal of Artificial Intelligence     Open Access   (Followers: 5)
Journal of Circuits, Systems, and Computers     Hybrid Journal   (Followers: 1)
Journal of Electrical and Electronics Engineering Research     Open Access   (Followers: 2)
Journal of Electrical Bioimpedance     Full-text available via subscription   (Followers: 2)
Journal of Electrical Engineering & Electronic Technology     Full-text available via subscription   (Followers: 1)
Journal of Electromagnetic Analysis and Applications     Open Access   (Followers: 3)
Journal of Electromagnetic Waves and Applications     Hybrid Journal   (Followers: 2)
Journal of Electronic Design Technology     Full-text available via subscription   (Followers: 1)
Journal of Electronics (China)     Hybrid Journal   (Followers: 2)
Journal of Field Robotics     Hybrid Journal   (Followers: 2)
Journal of Guidance, Control, and Dynamics     Full-text available via subscription   (Followers: 52)
Journal of Intelligent Procedures in Electrical Technology     Open Access  
Journal of Low Power Electronics     Full-text available via subscription   (Followers: 4)
Journal of Low Power Electronics and Applications     Open Access   (Followers: 1)

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IEEE Transactions on Power Electronics
   Journal TOC RSS feeds Export to Zotero [15 followers]  Follow    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 0885-8993
     Published by Institute of Electrical and Electronics Engineers (IEEE) Homepage  [172 journals]   [SJR: 3.308]   [H-I: 111]
  • IEEE Power Electronics Society Information
    • Pages: C3 - C3
      Abstract: Provides a listing of current committee members and society officers.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • Table of contents
    • Pages: C1 - C4
      Abstract: Presents the table of contents for this issue of the periodical.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • IEEE Transactions on Power Electronics publication information
    • Pages: C2 - C2
      Abstract: "Provides a listing of current staff, committee members and society officers."
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • Editorial Special Issue on Modular Multilevel Converters, 2015
    • Authors: Perez; M.A.;Bernet, S.;Rodriguez, J.;Kouro, S.;
      Pages: 1 - 3
      Abstract: The articles in this special issue focus on the latest achievements of modular multilevel converters regarding the development of new circuit configurations, converter models, modulation strategies, and control schemes.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • Circuit Topologies, Modeling, Control Schemes, and Applications of Modular
           Multilevel Converters
    • Authors: Perez; M.A.;Bernet, S.;Rodriguez, J.;Kouro, S.;Lizana, R.;
      Pages: 4 - 17
      Abstract: Modular multilevel converters have several attractive features such as a modular structure, the capability of transformer-less operation, easy scalability in terms of voltage and current, low expense for redundancy and fault tolerant operation, high availability, utilization of standard components, and excellent quality of the output waveforms. These features have increased the interest of industry and research in this topology, resulting in the development of new circuit configurations, converter models, control schemes, and modulation strategies. This paper presents a review of the latest achievements of modular multilevel converters regarding the mentioned research topics, new applications, and future trends.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • Modular Multilevel Converters for HVDC Applications: Review on Converter
           Cells and Functionalities
    • Authors: Nami; A.;Liang, J.;Dijkhuizen, F.;Demetriades, G.D.;
      Pages: 18 - 36
      Abstract: In this paper, the principle of modularity is used to derive the different multilevel voltage and current source converter topologies. The paper is primarily focused on high-power applications and specifically on high-voltage dc systems. The derived converter cells are treated as building blocks and are contributing to the modularity of the system. By combining the different building blocks, i.e., the converter cells, a variety of voltage and current source modular multilevel converter topologies are derived and thoroughly discussed. Furthermore, by applying the modularity principle at the system level, various types of high-power converters are introduced. The modularity of the multilevel converters is studied in depth, and the challenges as well as the opportunities for high-power applications are illustrated.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • Operation, Control, and Applications of the Modular Multilevel Converter:
           A Review
    • Authors: Debnath; S.;Qin, J.;Bahrani, B.;Saeedifard, M.;Barbosa, P.;
      Pages: 37 - 53
      Abstract: The modular multilevel converter (MMC) has been a subject of increasing importance for medium/high-power energy conversion systems. Over the past few years, significant research has been done to address the technical challenges associated with the operation and control of the MMC. In this paper, a general overview of the basics of operation of the MMC along with its control challenges are discussed, and a review of state-of-the-art control strategies and trends is presented. Finally, the applications of the MMC and their challenges are highlighted.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • A Bidirectional Modular Multilevel DC–DC Converter of Triangular
    • Authors: Filsoof; K.;Lehn, P.W.;
      Pages: 54 - 64
      Abstract: In this paper, a novel bidirectional modular multilevel dc–dc converter is proposed. The proposed topology, named the triangular modular multilevel dc–dc converter (TMMC), can achieve equal power sharing among its modules over a broad range of conversion ratios. The proposed control algorithm provides localized control of modules which enhances the converter’s dynamic performance and design flexibility. A 1.7-kW experimental implementation of the converter is shown to achieve an efficiency of 95.9% and 96.2% in step-up and step-down modes, respectively. Significant reductions in the input current and output voltage ripples are observed through the interleaved operation of the converter. The TMMC also provides multiple fixed voltage nodes which makes it suitable as a multiple-input multiple-output converter.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • Hybrid Multilevel Converter With Cascaded H-bridge Cells for HVDC
           Applications: Operating Principle and Scalability
    • Authors: Adam; G.G.P.;Abdelsalam, I.;Ahmed, K.;Williams, B.W.;
      Pages: 65 - 77
      Abstract: Hybrid multilevel converters are contemplated in an attempt to optimize the performance of voltage source converters in terms of magnitude of semiconductor losses and converter footprint, and to achieve additional features such as dc short circuit proof, which is essential for a high integrity multiterminal HVDC grid. Therefore, this paper considers an emerging hybrid cascaded converter that offers the dc side short circuit proof feature at reduced loss and footprint compared to the existing multilevel and other hybrid converters. Its operating principle, modulation, and capacitor voltage balancing strategies are described in detail. Furthermore, hybrid converter scalability to high voltage applications is investigated. The validity of the modulation and capacitor voltage strategy presented are confirmed using simulation and experimentation. The hybrid cascaded converter is extendable to a large number of cells, making it applicable to high voltage applications, and operation is independent of modulation index and power factor. On these ground, the converter is expected to be applicable for both real and reactive power applications.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • A New Resonant Modular Multilevel Step-Down DC–DC Converter with
    • Authors: Zhang; X.;Green, T.C.;Junyent-Ferre, A.;
      Pages: 78 - 88
      Abstract: Modular multilevel converters (MMCs) have become increasingly interesting in dc–dc applications, as there is a growing demand for dc–dc converters in high-voltage applications. Power electronics transformers can be used for high step-down ratio dc–dc power conversion, with high power rating and efficiency achieved. However, this arrangement requires a large number of high isolation voltage transformers and a complicated balancing control scheme. To provide a simple solution with inherent voltage balancing, this paper presents a new resonant MMC topology for dc–dc conversion. The proposed converter achieves high-voltage step-down ratio depending on the number of submodules. The converter also exhibits simplicity and scalability with no necessary requirement of high-voltage isolation transformers. By using phase-shift control, a much higher converter operating frequency is achieved compared to the switching frequency. Resonant conversion is achieved between the series inductor and submodule capacitors. The operation principle and theoretical analysis are presented in this paper, which have been verified by experimental results based on a bench-scale prototype.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • Isolated DC/DC Structure Based on Modular Multilevel Converter
    • Authors: Kenzelmann; S.;Rufer, A.;Dujic, D.;Canales, F.;de Novaes, Y.R.;
      Pages: 89 - 98
      Abstract: In the future, new aspects from decentralized generation using different dc voltage levels are expected to influence the general concept of power exchange. Converter are needed to adapt the voltage between low voltage (LV), medium voltage (MV), and high voltage (HV). In this paper, a galvanic isolated bidirectional dc/dc converter based on the modular multilevel converter is studied, with a large potential for secure and flexible dc power flow control. The use of medium frequency transformation allows savings in copper and iron. A fundamental frequency modulation method is introduced for the presented converter, that enables variable stepup or step-down between primary and secondary dc voltage in discrete steps. The balancing mechanism of the internal power storage components is explained and verified by simulation and experiment.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • Modular Multilevel DC/DC Converters With Phase-Shift Control Scheme for
           High-Voltage DC-Based Systems
    • Authors: Li; W.;Jiang, Q.;Mei, Y.;Li, C.;Deng, Y.;He, X.;
      Pages: 99 - 107
      Abstract: In this paper, by investigating the topology derivation principle of the phase-shift-controlled three-level dc/dc converters, the modular multilevel dc/dc converters, by integrating the full-bridge converters and three-level flying capacitor circuit, are proposed for the high step-down and high power dc-based systems. The high switch voltage stress in the primary side is effectively reduced by the full-bridge modules in series. Therefore, the low-voltage-rated power devices can be employed to obtain the benefits of low conduction losses. More importantly, the voltage autobalance ability among the cascaded modules is achieved by the inherent flying capacitor, which removes the additional possible active components or control loops. In addition, zero-voltage-switching performance for all the active switches can be provided due to the phase-shift control scheme, which can reduce the switching losses. The circuit operation and converter performance are analyzed in detail. Finally, the performance of the presented converter is verified by the simulation and experimental results from a 2-kW prototype.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • Quasi Two-Level Operation of Modular Multilevel Converter for Use in a
           High-Power DC Transformer With DC Fault Isolation Capability
    • Authors: Gowaid; I.A.;Adam, G.P.;Massoud, A.M.;Ahmed, S.;Holliday, D.;Williams, B.W.;
      Pages: 108 - 123
      Abstract: DC fault protection is one challenge impeding the development of multiterminal dc grids. The absence of manufacturing and operational standards has led to many point-to-point HVDC links built at different voltage levels, which creates another challenge. Therefore, the issues of voltage matching and dc fault isolation are undergoing extensive research and are addressed in this paper. A quasi two-level operating mode of the modular multilevel converter is proposed, where the converter generates a square wave with controllable dv/dt by employing the cell voltages to create transient intermediate voltage levels. Cell capacitance requirements diminish and the footprint of the converter is reduced. The common-mode dc component in the arm currents is not present in the proposed operating mode. The converter is proposed as the core of a dc to dc transformer, where two converters operating in the proposed mode are coupled by an ac transformer for voltage matching and galvanic isolation. The proposed dc transformer is shown to be suitable for high-voltage high-power applications due to the low-switching frequency, high efficiency, modularity, and reliability. The dc transformer facilitates dc voltage regulation and near instant isolation of dc faults within its protection zone. Analysis and simulations confirm these capabilities in a system-oriented approach.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • Comparison of the Modular Multilevel DC Converter and the Dual-Active
           Bridge Converter for Power Conversion in HVDC and MVDC Grids
    • Authors: Engel; S.P.;Stieneker, M.;Soltau, N.;Rabiee, S.;Stagge, H.;De Doncker, R.W.;
      Pages: 124 - 137
      Abstract: It is expected that in the near future the use of high-voltage dc (HVDC) transmission and medium-voltage dc (MVDC) distribution technology will expand. This development is driven by the growing share of electrical power generation by renewable energy sources that are located far from load centers and the increased use of distributed power generators in the distribution grid. Power converters that transfer the electric energy between voltage levels and control the power flow in dc grids will be key components in these systems. The recently presented modular multilevel dc converter (M2DC) and the three-phase dual-active bridge converter (DAB) are benchmarked for this task. Three scenarios are examined: a 15 MW converter for power conversion from an HVDC grid to an MVDC grid of a university campus, a gigawatt converter for feeding the energy from an MVDC collector grid of a wind farm into the HVDC grid, and a converter that acts as a power controller between two HVDC grids with the same nominal voltage level. The operation and degrees of freedom of the M2DC are investigated in detail aiming for an optimal design of this converter. The M2DC and the DAB converter are thoroughly compared for the given scenarios in terms of efficiency, amount of semiconductor devices, and expense on capacitive storage and magnetic components.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • A New Family of Modular Multilevel Converter Based on Modified
           Flying-Capacitor Multicell Converters
    • Authors: Dargahi; V.;Sadigh, A.;Abarzadeh, M.;Eskandari, S.;Corzine, K.A.;
      Pages: 138 - 147
      Abstract: Modular multilevel converters (MMCs) are one of the next-generation multilevel converters intended for medium/high-voltage high-power market. This paper initially studies a modified topology for flying-capacitor multicell converters (FCMCs) as a modular submultilevel module. The main advantage of the modified FCMC, in comparison with the conventional one, is that the number and voltage rating of the required dc voltage sources are halved. Afterward, the MMC that comprises the series connection of the modified FCMCs used as submultilevel modules is proposed. Simulation results and experimental measurements taken from the four-cell-five-level laboratory prototype system of the modified FCMC as a modular submultilevel module are presented in order to validate its performance and advantages. Moreover, simulation results and experimental measurements of three cascaded two-cell-three-level modules (ultimately seven-level proposed MMC) and four cascaded two-cell-three-level modules (ultimately nine-level proposed MMC) are presented in order to validate its viability, merits and the proposed control strategy.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • A Modular Multilevel DC/DC Converter With Fault Blocking Capability for
           HVDC Interconnects
    • Authors: Kish; G.J.;Ranjram, M.;Lehn, P.W.;
      Pages: 148 - 162
      Abstract: This paper introduces a modular multilevel dc/dc converter, termed the DC-MMC, that can be deployed to interconnect HVDC networks of different or similar voltage levels. Its key features include: 1) bidirectional power flow; 2) step-up and step-down operation; and 3) bidirectional fault blocking similar to a dc circuit breaker. The kernel of the DC-MMC is a new class of bidirectional single-stage dc/dc converters utilizing interleaved strings of cascaded submodules. The DC-MMC operation is analyzed and an open loop voltage control strategy that ensures power balance of each submodule capacitor via circulating ac currents is proposed. Simulations performed in PLECS validate the DC-MMC’s principle of operation and the proposed control strategy. Experimental results for a 4-kW laboratory prototype illustrate the single-stage dc/dc conversion process for both step-down and step-up operating modes.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • Analysis and Control of Modular Multilevel Converters With Integrated
           Battery Energy Storage
    • Authors: Vasiladiotis; M.;Rufer, A.;
      Pages: 163 - 175
      Abstract: Multilevel converters and battery energy storage systems are key components in present and future medium voltage networks, where an important integration of renewable energy sources takes place. The modular multilevel converter offers the capability of embedding such energy storage elements in a split manner, given the existence of several submodules operating at significantly lower voltages. This paper analyzes such a converter structure under different operating modes. In order to eliminate the low-frequency components of the submodule output currents, the latter are interfaced to the batteries by means of nonisolated dc/dc converters. Control algorithms are developed for the balancing of the battery state of charges and the respective gain limitations are established. Unbalanced grid conditions are also taken into account through the theory of symmetrical components and solutions are proposed. Finally, the development of a down-scaled prototype is described and experimental results are presented.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • Decoupled Active and Reactive Power Control for Large-Scale Grid-Connected
           Photovoltaic Systems Using Cascaded Modular Multilevel Converters
    • Authors: Liu; L.;Li, H.;Xue, Y.;Liu, W.;
      Pages: 176 - 187
      Abstract: Large-scale grid-connected photovoltaic (PV) systems significantly contribute to worldwide renewable energy growth and penetration, which has inspired the application of cascaded modular multilevel converters due to their unique features such as modular structures, enhanced energy harvesting capability, scalability and so on. However, power distribution and control in the cascaded PV system faces tough challenge on output voltage overmodulation when considering the varied and nonuniform solar energy on segmented PV arrays. This paper addresses this issue and proposes a decoupled active and reactive power control strategy to enhance system operation performance. The relationship between output voltage components of each module and power generation is analyzed with the help of a newly derived vector diagram which illustrates the proposed power distribution principle. On top of this, an effective control system including active and reactive components extraction, voltage distribution and synthesization, is developed to achieve independent active and reactive power distribution and mitigate the aforementioned issue. Finally, a 3-MW, 12-kV PV system with the proposed control strategy is modeled and simulated in MATLAB and PSIM cosimulation platform. A downscaled PV system including two cascaded 5-kW converters with proposed control strategy is also implemented in the laboratory. Simulation and experimental results are provided to demonstrate the effectiveness of the proposed control strategy for large-scale grid-connected cascaded PV systems.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • Reactive Power Compensation and Optimization Strategy for Grid-Interactive
           Cascaded Photovoltaic Systems
    • Authors: Liu; L.;Li, H.;Xue, Y.;Liu, W.;
      Pages: 188 - 202
      Abstract: Cascaded multilevel converter structure can be appealing for high-power solar photovoltaic (PV) systems thanks to its modularity, scalability, and distributed maximum power point tracking (MPPT). However, the power mismatch from cascaded individual PV converter modules can bring in voltage and system operation issues. This paper addresses these issues, explores the effects of reactive power compensation and optimization on system reliability and power quality, and proposes coordinated active and reactive power distribution to mitigate this issue. A vector method is first developed to illustrate the principle of power distribution. Accordingly, the relationship between power and voltage is analyzed with a wide operation range. Then, an optimized reactive power compensation algorithm (RPCA) is proposed to improve the system operation stability and reliability, and facilitate MPPT implementation for each converter module simultaneously. Furthermore, a comprehensive control system with the RPCA is designed to achieve effective power distribution and dynamic voltage regulation. Simulation and experimental results are presented to demonstrate the effectiveness of the proposed reactive power compensation approach in grid-interactive cascaded PV systems.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • Modular Multilevel Converter With Series and Parallel Module Connectivity:
           Topology and Control
    • Authors: Goetz; S.M.;Peterchev, A.V.;Weyh, T.;
      Pages: 203 - 215
      Abstract: This paper introduces a novel modular multilevel series/parallel converter that allows switching modules dynamically not only in series, as in the traditional modular multilevel converter (M2C), but also in parallel. As in M2C, the semiconductor voltages do not exceed the module capacitor voltage for any module state. While the new topology is a generalization of M2C and could, therefore, be operated identically to it, the additional states provide degrees of freedom that the controller can dynamically employ to achieve several advantages. Whereas in M2C many modules are bypassed if the instantaneous converter voltage is lower than the system's peak voltage, the parallel connectivity enables these modules to contribute to the current load, thus reducing conduction losses. In addition, the parallel configuration of modules can be used for balancing the modules’ state of charge (SOC). The parallelization losses are moderate or negligible, dependent on the switching rate. Since the parallel connection of capacitors can ensure balancing, it enables stable operation of a multilevel converter without the need for monitoring the module SOCs. While such economical control hardware may be appropriate for low-power systems, we also present more sophisticated control that uses the additional degrees of freedom to minimize losses. Finally, we point to further extensions of the circuit topology to multipole module connectivity that could enable additional functionality and applications.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • Hybrid AC Power Source Based on Modular Multilevel Converter and Linear
    • Authors: da Silva; G.S.;Beltrame, R.C.;Schuch, L.;Rech, C.;
      Pages: 216 - 226
      Abstract: This paper presents a hybrid amplifier for an ac power source (ACPS). The topology is composed of a modular multilevel converter (MMC), operating as main amplifier, connected in series with a linear power amplifier (LPA), which operates as correction amplifier. This way, it is possible to gather the modularity, reliability, and high efficiency provided by the MMC and the high waveform fidelity provided by the LPA. Additionally, it is possible to reproduce a voltage waveform with a high bandwidth and, differently from previous works, with a topology that requires a unique dc voltage source for the main amplifier. The inner current and the submodule capacitor voltages are controlled in the MMC. Meanwhile, the LPA is controlled to define the output voltage. A design methodology and experimental results are included to demonstrate the operation of the ACPS topology.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • Optimal Selection of the Average Capacitor Voltage for Variable-Speed
           Drives With Modular Multilevel Converters
    • Authors: Antonopoulos; A.;Angquist, L.;Harnefors, L.;Nee, H.;
      Pages: 227 - 234
      Abstract: Variable-speed drives have reduced voltage requirements when operating below the base speed. In a modular-multilevel-converter-based (M2C-based) motor drive, it is then possible to operate with reduced voltage in the submodule capacitors, than at the base speed. In this sense, a greater capacitor-voltage ripple can be accommodated, without exceeding the maximum peak-capacitor voltage. This paper presents an analytical investigation for the optimal selection of the average capacitor voltage for M2Cs, when the motor is operating with rated torque, below the base speed. This method does not require any power exchange between the converter arms, so it keeps the conduction losses at the minimum level. Additionally, the method decreases the switching losses, due to the decreased capacitor-voltage level. The overall ratings of the converter remain the same as in the base-speed operation. It is shown that this method can be applied at a speed range between the base speed and down to approximately one third of it, i.e., an operating range that covers the requirements for typical pump- and fan-type applications. The results obtained from the analytical investigation are experimentally verified on a down-scaled laboratory prototype M2C.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • Modular Multilevel Converter With an Adaptive Observer of Capacitor
    • Authors: Nademi; H.;Das, A.;Norum, L.E.;
      Pages: 235 - 248
      Abstract: A modular multilevel converter (MMC) is an attractive solution for power conversion without transformers. The MMC consists of cascade connections of floating dc capacitors. In this paper, an adaptive observer design has been proposed to estimate the capacitor voltages from the measurement of arm currents. This work introduces the capacitance value of the cell capacitors as a parameter uncertainty for making the system performance robust with unknown constant parameters. It may be used for predictive control, condition monitoring for capacitors, and diagnosis check for capacitor health. In addition, a pulsewidth modulation (PWM) technique for MMC has been explored. The PWM technique is performed using a carrier-based level-shifted PWM strategy. It does not necessitate the calculation of duty cycles, and can be easily implemented in a DSP. By using the PWM technique, harmonics in the phase voltage is shifted to twice the switching frequency. Theoretical analysis is included in this paper for showing stability and convergence of the proposed observer. Analytical expressions are verified by simulation and experimental results.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • Global Asymptotic Stability of Current-Controlled Modular Multilevel
    • Authors: Harnefors; L.;Antonopoulos, A.;Ilves, K.;Nee, H.-P.;
      Pages: 249 - 258
      Abstract: In this paper, previously developed stability results for open-loop sum-capacitor-voltage control of modular multilevel converters are extended. To give improved damping, circulating-current feedback is included in the control law. With the output-current control loop and a first-order measurement lag taken into account, global asymptotic stability is proven. Careful consideration of the on-line sum-capacitor-voltage reference computation is given, since this is the most critical part of the control system.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • Real-Time Simulation of MMCs Using CPU and FPGA
    • Authors: Saad; H.;Ould-Bachir, T.;Mahseredjian, J.;Dufour, C.;Dennetiere, S.;Nguefeu, S.;
      Pages: 259 - 267
      Abstract: Modular multilevel converter (MMC) structures are composed of several hundreds to thousands of half-bridge converters. Such large numbers of power switches and electrical nodes introduce important numerical challenges for the computation of electromagnetic transients. The problem becomes particularly more complex for the real-time simulations. This paper presents a feasibility study on the real-time simulation of the MMC models. CPU-based and field-programmable gate array-based implementations are proposed and evaluated for the MMCs having up to 401 levels. The study also provides guidelines for the real-time simulation platform requirements to simulate these MMC models.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • Analysis and Operation of Modular Multilevel Converters With Phase-Shifted
           Carrier PWM
    • Authors: Ilves; K.;Harnefors, L.;Norrga, S.;Nee, H.;
      Pages: 268 - 283
      Abstract: Many publications have been presented on the modulation and control of the modular multilevel converter, some of which are based on phase-shifted carrier modulation. This paper presents an analysis of how the switching frequency affects the capacitor voltages, circulating currents, and alternating voltages using phase-shifted carrier modulation. It is found that switching frequencies that are integer multiples of the fundamental frequency should be avoided as they can cause the capacitor voltages to diverge. Suitable switching frequencies are derived for which the arm and line quantities will be periodic with symmetric operating conditions in the upper and lower arms. Thus, the practical outcome of this paper is a detailed description of how the switching frequency should be chosen in order to achieve advantageous operating conditions. The theoretical results from the analysis are validated by both simulations and experimental results.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • Elimination of DC-Link Current Ripple for Modular Multilevel Converters
           With Capacitor Voltage-Balancing Pulse-Shifted Carrier PWM
    • Authors: Deng; F.;Chen, Z.;
      Pages: 284 - 296
      Abstract: The modular multilevel converter (MMC) is attractive for medium- and high-power applications because of its high modularity, availability, and power quality. In this paper, the current ripple on the dc link of the three-phase MMC derived from the phase-shifted carrier-based pulse-width modulation scheme is analyzed. A control strategy is proposed for the current ripple elimination. Through the regulation of the phase-shifted angles of the carrier waves in the three phases of the MMC, the current ripple on the dc link of the three-phase MMC can be effectively eliminated. Simulations and experimental studies of the MMC were conducted, and the results confirm the effectiveness of the proposed current ripple elimination control.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • Analysis of the Phase-Shifted Carrier Modulation for Modular Multilevel
    • Authors: Li; B.;Yang, R.;Xu, D.;Wang, G.;Wang, W.;Xu, D.;
      Pages: 297 - 310
      Abstract: The modular multilevel converter (MMC) is an emerging topology for high-power applications and is considered as the development trend of the high-voltage power converters. In this paper, general implementation of the phase-shifted carrier (PSC) modulation with a capacitor voltage balancing method for MMC is first introduced. Then, the mathematical analysis of PSC modulation for MMC is performed to identify the PWM harmonic characteristics of the output voltage and the circulating current. Moreover, influence of the carrier displacement angle between the upper and lower arms on these harmonics is also studied. Using this analysis, the optimum displacement angles are specified for the output voltage harmonics minimization and the circulating current harmonics cancellation, respectively. The harmonic features of the line-to-line voltage and the dc-link current are also investigated. Moreover, an extension of the PSC modulation for MMC with full-bridge submodules is also proposed which can increase the equivalent switching frequency of the output voltage and circulating current by two times compared with the conventional MMC. Finally, the findings are verified experimentally on a prototype of MMC.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • Tolerance Band Modulation Methods for Modular Multilevel Converters
    • Authors: Hassanpoor; A.;Angquist, L.;Norrga, S.;Ilves, K.;Nee, H-.P.;
      Pages: 311 - 326
      Abstract: Modular multilevel converters (M2Cs) are increasingly used in high-voltage direct current (HVDC) systems. The efficiency of M2Cs is influenced by the modulation and cell selecting methods, which determines the switching frequency and capacitor voltage ripple in the converter station. A new approach to modulation of the M2C is presented in this paper. Tolerance band methods are employed to obtain the switching instants, and also cell selection. The proposed methods overcome the modulation problem for converters with few cells on one hand and also reduce the sorting efforts for cell balancing purposes of many cells converter on the other hand. Three different algorithms are also proposed to balance the cell capacitor voltages. The evaluation is done in time-domain simulation by which the performance of each method is studied in both the steady-state and transient cases. It is observed that using tolerance band methods not only reduces the switching frequency but also allows for handling severe fault cases in a grid-connected system. Eventually, the most promising tolerance band method has been implemented and verified in a real-time digital simulator, RTDS®. The average switching frequency of 70 Hz has been achieved for the system under study, while the capacitor voltage ripple is limited to 10% of the nominal cell voltage.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • Modulation and Closed-Loop-Based DC Capacitor Voltage Control for MMC With
           Fundamental Switching Frequency
    • Authors: Du; S.;Liu, J.;Liu, T.;
      Pages: 327 - 338
      Abstract: This paper presents a novel modulation and capacitor voltage control method for the modular multilevel converter (MMC) allowing the fixed switching frequency of 50 Hz. In the proposed modulation method, the switching angles are calculated through a new approach with reference to the nearest voltage level control. And then, every four pulse patterns are grouped together for averaging the dc and fundamental ac components in the output voltage of individual submodules. Accordingly, the absorbed power of each submodule could be self-balanced during few line periods simply by periodically swapping the pulse patterns. Moreover, the different power losses or different initial energy states of the submodules may also cause the dc capacitor voltage deviation although the absorbed power is equally distributed. Therefore, a closed-loop-based method of exchanging the leading or falling edges of pulse patterns is developed for dc capacitor voltage control. Simulation results show that the MMC circuit together with the proposed method functions very well in both rectifier and inverter modes. Experimental results on a single-phase MMC-based inverter with four submodules in one arm show the validity of the proposed method.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • Optimized Control Strategy Based on Dynamic Redundancy for the Modular
           Multilevel Converter
    • Authors: Liu; G.;Xu, Z.;Xue, Y.;Tang, G.;
      Pages: 339 - 348
      Abstract: Considering the synthetical effects of the ac system and the dc system, this paper proposes two novel indexes, the dynamic redundancy and the utilization ratio of the submodules. On this basis, the nearest level control is applied as the modulation method and an optimized control strategy based on the dynamic redundancy for the modular multilevel converter (MMC) is proposed. One of the main innovations is that the reference value of the capacitor voltage is derived according to the maximum output voltage of each converter arm and the safety margin which can be adjusted artificially. Unlike previous strategies, the redundancy can be adjusted dynamically, and the utilization ratio of the submodules can be effectively improved. In addition, the capacitor voltage and the inner stress are reduced, and the fault ride-through capability of the system can be enhanced. In particular, the strategy under abnormal operating conditions is also detailed in this paper. A model of two-terminal MMC-high-voltage direct current system is built in PSCAD/EMTDC, and the simulation result proves the validity and the feasibility of the proposed strategy.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • Cascaded Control System of the Modular Multilevel Converter for Feeding
           Variable-Speed Drives
    • Authors: Kolb; J.;Kammerer, F.;Gommeringer, M.;Braun, M.;
      Pages: 349 - 357
      Abstract: The modular multilevel converter (MMC) is an upcoming topology for high-power drive applications especially in the medium voltage range. This paper presents the design process of a holistic control system for a MMC to feed variable-speed drives. First, the design of the current control for the independent adjustment of several current components is derived from the analysis of the equivalent circuits. Second, the current and voltage components for balancing the energies in the arms of the MMC are identified systematically by the investigation of the transformed arm power components. These fundamentals lead to the design of the cascaded control structure, which allows the balancing task in the whole operating range of a three-phase machine. The control system ensures a dynamic balancing of the energies in the cells of the MMC at minimum necessary internal currents over the complete frequency range. Simultaneously, all other circulating current components are avoided to minimize current stress and additional voltage pulsations. The performance of the control system is finally validated by measurements on a low-voltage MMC prototype, which feeds a field-oriented controlled induction machine.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • An Improved Control System for Modular Multilevel Converters with New
           Modulation Strategy and Voltage Balancing Control
    • Authors: Fan; S.;Zhang, K.;Xiong, J.;Xue, Y.;
      Pages: 358 - 371
      Abstract: Modular multilevel converter (MMC) has become one of the most promising converter topologies for future high-power applications. A challenging issue of the MMC is the voltage balancing among arm capacitors. A good overall control system is also vital for the MMC, which should be based on sound mathematical model, readily adaptable for different applications, and capable of high performance. This paper presents a general control structure for MMC inverters, which is suitable for both voltage-based and energy-based control methods, and includes voltage balancing between the upper and lower arms. A new method for voltage balancing among arm capacitors, which is based on an improved pulse-width modulation, is also presented. The proposed method avoids some major disadvantages found in present voltage balancing methods, such as dependence on computation-intensive voltage sorting algorithms, extra switching actions, interference with output voltage, etc. Furthermore, all switching actions are evenly distributed among power devices. The proposed control system as a whole can serve as a promising solution for practical applications, especially when the number of submodules is fairly high. Simulation and experimental results verify the effectiveness of the proposed methods.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • Control of Parallel-Connected Modular Multilevel Converters
    • Authors: Gao; F.;Niu, D.;Tian, H.;Jia, C.;Li, N.;Zhao, Y.;
      Pages: 372 - 386
      Abstract: The modular multilevel converter (MMC) is an emerging and highly attractive multilevel converter topology for high-voltage and high-power applications. This paper proposes the control method of parallel-connected modular multilevel converters (parallel-MMCs), which assumes that the multiple MMCs are directly connected at both ac and dc sides to effectively enhance the power rating as expected. Two key problems were first solved for the parallel-MMCs under the normal operation conditions: voltage balancing of submodules and mitigation of circulating currents, where the novel transformed third-order harmonic resonant controller in the synchronous reference frame was employed to mitigate the dominant second-order and fourth-order circulating currents and a sixth-order harmonic resonant controller is used to attenuate the zero-sequence sixth-order circulating current existed in all phase currents per MMC. Considering the high risk of switches fault in the parallel-MMCs, the fault-tolerant operation schemes were then proposed in this paper to address the major concerns of open-circuit and short-circuit switch fault in a submodule, respectively. Carefully controlling the healthy submodules and the corresponding phase arms, the parallel-MMCs can successfully maintain their balanced capacitor voltages and mitigate the circulating currents with the qualified output waveform obtained. In addition, the parallel configuration of MMCs provides the unique solution for the short-circuit switch fault operation which was seldom discussed in the published literature works with respect to the MMC fault-tolerant operation schemes. MATLAB simulations and the constructed experimental prototype have verified the performance of the proposed control strategy.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • Circulating Current Suppressing Strategy for MMC-HVDC Based on Nonideal
           Proportional Resonant Controllers Under Unbalanced Grid Conditions
    • Authors: Li; S.;Wang, X.;Yao, Z.;Li, T.;Peng, Z.;
      Pages: 387 - 397
      Abstract: Modular multilevel converter (MMC) is considered as a promising topology for voltage-source converter (VSC) high-voltage, direct current (HVDC) applications. This paper presents a new control strategy for MMC-HVDC under unbalanced grid conditions. First, a new inner loop current control strategy based on nonideal proportional resonant (PR) controllers in stationary αβ frame is designed, which is more concise compared to the existing dual sequence current control scheme. Second, an analytical expression for circulating current is obtained which shows that the circulating currents will be asymmetric under unbalanced grid conditions and can be decomposed into positive-, negative-, and zero-sequence component. In order to suppress all these components, a new circulating current suppressing strategy is analyzed and designed also based on nonideal PR controllers. Application of nonideal PR controllers makes the control system well adapt to the fluctuation of grid frequency. The effectiveness of the proposed control strategy is verified through a simulation case of a 251-level MMC-HVDC transmission system using real-time digital simulator.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • Analysis and Trajectory Tracking Control of a Modular Multilevel Converter
    • Authors: Fehr; H.;Gensior, A.;Muller, M.;
      Pages: 398 - 407
      Abstract: The paper presents a control scheme for modular multilevel converters (M2Cs) where the property of differential flatness of the model of the load connected to the converter is exploited. This is done by encapsulating the subsystem of the load such that it appears in the model of the converter as a current source. The controller comprises a trajectory planning algorithm and a tracking controller. This way of modeling leads to a decoupling of the controller for the load and the controller for the converter, especially for the design of the tracking controller. All developments rely on a single-phase model of an M2C, and it is shown that it shares the properties relevant for control design with the original three-phase model. All results are verified experimentally.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • Characteristic Investigation and Control of a Modular Multilevel
           Converter-Based HVDC System Under Single-Line-to-Ground Fault Conditions
    • Authors: Shi; X.;Wang, Z.;Liu, B.;Liu, Y.;Tolbert, L.M.;Wang, F.;
      Pages: 408 - 421
      Abstract: This paper presents the analysis and control of a multilevel modular converter (MMC)-based HVDC transmission system under three possible single-line-to-ground fault conditions, with special focus on the investigation of their different fault characteristics. Considering positive-, negative-, and zero-sequence components in both arm voltages and currents, the generalized instantaneous power of a phase unit is derived theoretically according to the equivalent circuit model of the MMC under unbalanced conditions. Based on this model, a novel double-line frequency dc-voltage ripple suppression control is proposed. This controller, together with the negative- and zero-sequence current control, could enhance the overall fault-tolerant capability of the HVDC system without additional cost. To further improve the fault-tolerant capability, the operation performance of the HVDC system with and without single-phase switching is discussed and compared in detail. Simulation results from a three-phase MMC-HVDC system generated with MATLAB/Simulink are provided to support the theoretical analysis and proposed control schemes.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • Experimental Comparison of Model Predictive Control and Cascaded Control
           of the Modular Multilevel Converter
    • Authors: Bocker; J.;Freudenberg, B.;The, A.;Dieckerhoff, S.;
      Pages: 422 - 430
      Abstract: This paper evaluates two different concepts for the control of the modular multilevel converter (MMC). Generally aiming at medium voltage applications, the considered MMC topology has a low number of submodules, and a pulse-width modulation (PWM) scheme is applied. A model predictive control (MPC) algorithm is developed and experimentally compared to a cascaded control scheme based on conventional PI controllers, which has been proposed by Hagiwara and Akagi. Steady-state and dynamic system performance as well as computational power requirements are discussed. The basis for the comparison is a scaled converter test bench operating from 560-V dc voltage.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • Model Predictive Direct Current Control of Modular Multilevel Converters:
           Modeling, Analysis, and Experimental Evaluation
    • Authors: Riar; B.S.;Geyer, T.;Madawala, U.K.;
      Pages: 431 - 439
      Abstract: Modular multilevel converters (M2LCs) are typically controlled by a hierarchical control scheme, which essentially requires at least two control loops: one to control the load current and another to control circulating currents. This paper presents an M2LC with a single controller, which is based on model predictive direct current control (MPDCC) with long prediction horizons. The proposed MPDCC scheme maintains the load current within tight bounds around sinusoidal references and minimizes capacitor voltage variations and circulating currents. An internal prediction model of the M2LC is used to minimize the number of switching transitions for a given current ripple at steady state while providing a fast current response during transient conditions. A state-space model, which is generalized for an $N$ number of modules per each arm of the M2LC, is also presented to investigate the dynamic behavior of arm currents and capacitor voltages. Simulated performance of the converter, under various operating conditions, is presented in comparison to measured performance of a single-phase, three-level 860-VA M2LC prototype to demonstrate the proposed MPDCC philosophy.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • Predictive Sorting Algorithm for Modular Multilevel Converters Minimizing
           the Spread in the Submodule Capacitor Voltages
    • Authors: Ilves; K.;Harnefors, L.;Norrga, S.;Nee, H-.P.;
      Pages: 440 - 449
      Abstract: The balancing of the capacitor voltages in modular multilevel converters becomes increasingly difficult when the switching frequency is reduced. Typically, a reduced switching frequency will increase the spread in the capacitor voltages and, thus, the voltage ripple in the individual submodules. This paper presents a capacitor voltage balancing strategy which aims to combine a low switching frequency with a low capacitor-voltage ripple. This is done by a predictive algorithm that controls the converter in such a way that the stored charge in the submodule capacitors is evenly distributed among all the submodules when the capacitor voltages reach their maximum values. In this way, it is possible to limit the peak voltages in the submodule capacitors at switching frequencies as low as 2–3 times the fundamental switching frequency. The proposed capacitor voltage balancing strategy is validated by both simulations and experimental results with 130-Hz and 140-Hz switching frequency. In the simulations, the capacitor voltage ripple was reduced by 24% compared to the case when a conventional sorting algorithm is used, and the experimental results show that it is possible to combine the proposed voltage balancing strategy with a circulating-current controller.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • A Simplified Nearest Level Control (NLC) Voltage Balancing Method for
           Modular Multilevel Converter (MMC)
    • Authors: Meshram; P.M.;Borghate, V.B.;
      Pages: 450 - 462
      Abstract: In this paper, a simplified nearest level control balancing method for modular multilevel converter is presented. The proposed method neither requires individual sorting of the submodule voltages nor the redundancy of the switching states. Once the sorting of the submodules is done on the basis of the number of the submodules to be switched on, the identifications of the submodules can be carried out throughout the stages of the implementation of the this method. The proposed method also does not require the individual submodule status in the gate pulse generation stage. The gate logic in the presented method can be implemented with the help of the switching states of the voltage levels. Those simplifications and removing of the some of the stages by the proposed balancing method may ease and lead to the less processor time at the implementation level. The pictorial presentation further helps in consolidating the understanding of the different stages of the method. Rigorous simulations are carried out for open and one of the prominent closed-loop applications, i.e., modular multilevel converter-based high-voltage direct current to demonstrate the validity and effectiveness of the proposed simplified balancing method under normal and emergency conditions.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • Fast Sorting Method for Balancing Capacitor Voltages in Modular Multilevel
    • Authors: Siemaszko; D.;
      Pages: 463 - 470
      Abstract: The modular multilevel converter (MMC) is attracting more and more interest in high-power and high-voltage applications. Highly redundant, each arm of the converter is made of a large number of identical submodules with inner storage capability allowing to reach very high voltage without dc-link capacitor. The control of such a converter represents a challenge when it comes to the implementation of an MMC with a large number of submodules, namely in distributing the control tasks and handling the communicated values in-between controllers and submodules. This paper presents the details of an innovative submodule selection method for the submodule capacitor’s voltage balancing within one arm of an MMC. “The Tortoise and the Hare” sorting method shows very fast response, high reliability, and its implementation suits a large number of implemented submodules as for high-voltage dc applications. The proposed submodule capacitor’s balancing method is validated on a three-phase 10-kVA prototype with five submodules per arm.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • A Repetitive Control Scheme for Harmonic Suppression of Circulating
           Current in Modular Multilevel Converters
    • Authors: He; L.L.;Zhang, K.K.;Xiong, J.J.;Fan, S.S.;
      Pages: 471 - 481
      Abstract: In a modular multilevel converter (MMC), the interaction between switching actions and fluctuating capacitor voltages of the submodules results in second- and other even-order harmonics in the circulating currents. These harmonic currents will introduce extra power loss, increase current stress of power devices, and even cause instability during transients. Traditional methods for circulating current harmonic suppression have problems such as limited harmonic rejection capability, limited application area, and complex implementation. This paper presents a plug-in repetitive control scheme to solve the problem. It combines the high dynamics of PI controller and good steady-state harmonic suppression of the repetitive controller, and minimizes the interference between the two controllers. It is suitable for multiple harmonic suppression, easy to implement, and applicable for both single-phase and three-phase MMCs. Simulation and experimental results on a single-phase MMC inverter proved the validity of the proposed control method.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • Optimal Low Switching Frequency Pulsewidth Modulation of Nine-Level
           Cascade Inverter
    • Authors: Edpuganti; A.;Rathore, A.K.;
      Pages: 482 - 495
      Abstract: Synchronous optimal pulsewidth modulation (SOP) permits low switching frequency modulation of multilevel inverter for medium-voltage high-power industrial ac drives without compromising on total harmonic distortion (THD). An aim of our experiment was to operate a nine-level cascade inverter of an induction motor drive at an average device switching frequency limited to rated fundamental frequency by using SOP technique. To reduce the number of separate dc sources, a three-level diode clamped converter was used as a cell in the nine-level cascade inverter. Using SOP technique, optimal nine-level waveforms were obtained by ofline optimization assuming steady-state operation of the induction machine. The switching angles for each semiconductor switch are then obtained from optimal nine-level waveforms based on the criteria to minimize the switching frequency as well as unbalance in dc-link capacitor voltages. Experimental results obtained from the 1.5-kW induction motor drive show THD $
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • Optimal Low-Switching Frequency Pulsewidth Modulation of Medium Voltage
           Seven-Level Cascade-5/3H Inverter
    • Authors: Edpuganti; A.;Rathore, A.K.;
      Pages: 496 - 503
      Abstract: Low-switching frequency modulation of multilevel inverters for medium-voltage high-power industrial ac drives is essential to reduce switching losses and, thus, improve the overall energy efficiency of the system. However, minimizing the switching frequency increases the total harmonic distortion (THD) of machine currents. Synchronous optimal pulsewidth modulation (SOP) is an emerging technique for controlling multilevel inverters at low-switching frequency without compromising on the THD of machine currents. The goal of our experiment was to implement SOP technique for controlling seven-level cascade inverter for an induction motor drive at an average device switching frequency limited to rated fundamental frequency. First, optimal seven-level waveforms were obtained by ofline optimization assuming steady-state operating conditions. Then, the switching angles for each semiconductor device were obtained that ensure equal distribution of switching losses as well as minimal unbalance in dc-link capacitor voltages. The proposed SOP technique is validated by experimental results obtained from the seven-level cascade inverter feeding a 1.5-kW induction motor.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • Robust Control for PWM-Based DC–DC Buck Power Converters With
           Uncertainty Via Sampled-Data Output Feedback
    • Authors: Zhang; C.;Wang, J.;Li, S.;Wu, B.;Qian, C.;
      Pages: 504 - 515
      Abstract: This paper investigates the sampled-data output feedback control problem for dc–dc buck power converters taking consideration of components uncertainties. A reduced-order observer and a robust output feedback controller, both in the sampled-data form, have been explicitly constructed with strong robustness in the presence of uncertain parameters. A delicate stability analysis process is presented to show that, by carefully selecting the design gains and the tunable sampling period, the output voltage of the hybrid closed-loop dc–dc buck converter system will globally asymptotically tend to the desired value even though the separation principle is out of reach and the controller is only switched at the sampling points. The proposed controller consists of a set of linear difference equations which will lead to direct and easier digital implementation. Numerical simulations and experimental results are shown to illustrate the performance of the proposed control scheme.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
  • IEEE Xplore Digital Library
    • Pages: 516 - 516
      Abstract: Advertisement: IEEE Xplore digital library. Driving research at the world's leading universities and institutions.
      PubDate: Jan. 2015
      Issue No: Vol. 30, No. 1 (2015)
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