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  Subjects -> ELECTRONICS (Total: 207 journals)
Showing 1 - 200 of 277 Journals sorted alphabetically
Acta Electronica Malaysia     Open Access  
Advanced Materials Technologies     Hybrid Journal   (Followers: 1)
Advances in Biosensors and Bioelectronics     Open Access   (Followers: 9)
Advances in Electrical and Electronic Engineering     Open Access   (Followers: 10)
Advances in Electronics     Open Access   (Followers: 101)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 9)
Advances in Microelectronic Engineering     Open Access   (Followers: 13)
Advances in Power Electronics     Open Access   (Followers: 44)
Advancing Microelectronics     Hybrid Journal  
American Journal of Electrical and Electronic Engineering     Open Access   (Followers: 28)
Annals of Telecommunications     Hybrid Journal   (Followers: 9)
APSIPA Transactions on Signal and Information Processing     Open Access   (Followers: 8)
Archives of Electrical Engineering     Open Access   (Followers: 16)
Australian Journal of Electrical and Electronics Engineering     Hybrid Journal  
Batteries     Open Access   (Followers: 9)
Batteries & Supercaps     Hybrid Journal   (Followers: 6)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 30)
Bioelectronics in Medicine     Hybrid Journal  
Biomedical Instrumentation & Technology     Hybrid Journal   (Followers: 5)
BULLETIN of National Technical University of Ukraine. Series RADIOTECHNIQUE. RADIOAPPARATUS BUILDING     Open Access   (Followers: 2)
Bulletin of the Polish Academy of Sciences : Technical Sciences     Open Access   (Followers: 1)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 46)
China Communications     Full-text available via subscription   (Followers: 9)
Chinese Journal of Electronics     Hybrid Journal  
Circuits and Systems     Open Access   (Followers: 17)
Control Systems     Hybrid Journal   (Followers: 318)
ECTI Transactions on Computer and Information Technology (ECTI-CIT)     Open Access  
ECTI Transactions on Electrical Engineering, Electronics, and Communications     Open Access   (Followers: 2)
Edu Elektrika Journal     Open Access   (Followers: 1)
Electrica     Open Access  
Electronic Design     Partially Free   (Followers: 123)
Electronic Markets     Hybrid Journal   (Followers: 7)
Electronic Materials Letters     Hybrid Journal   (Followers: 4)
Electronics     Open Access   (Followers: 111)
Electronics and Communications in Japan     Hybrid Journal   (Followers: 10)
Electronics For You     Partially Free   (Followers: 105)
Electronics Letters     Hybrid Journal   (Followers: 26)
Elektronika ir Elektortechnika     Open Access   (Followers: 6)
Elkha : Jurnal Teknik Elektro     Open Access  
Emitor : Jurnal Teknik Elektro     Open Access   (Followers: 6)
Energy Harvesting and Systems     Hybrid Journal   (Followers: 4)
Energy Storage     Hybrid Journal   (Followers: 2)
Energy Storage Materials     Full-text available via subscription   (Followers: 5)
EPE Journal : European Power Electronics and Drives     Hybrid Journal  
EPJ Quantum Technology     Open Access   (Followers: 1)
EURASIP Journal on Embedded Systems     Open Access   (Followers: 10)
Facta Universitatis, Series : Electronics and Energetics     Open Access  
Foundations and Trends® in Communications and Information Theory     Full-text available via subscription   (Followers: 6)
Foundations and Trends® in Signal Processing     Full-text available via subscription   (Followers: 9)
Frequenz     Hybrid Journal   (Followers: 1)
Frontiers of Optoelectronics     Hybrid Journal   (Followers: 1)
IACR Transactions on Symmetric Cryptology     Open Access   (Followers: 1)
IEEE Antennas and Propagation Magazine     Hybrid Journal   (Followers: 110)
IEEE Antennas and Wireless Propagation Letters     Hybrid Journal   (Followers: 85)
IEEE Embedded Systems Letters     Hybrid Journal   (Followers: 54)
IEEE Journal of Electromagnetics, RF and Microwaves in Medicine and Biology     Hybrid Journal   (Followers: 3)
IEEE Journal of Emerging and Selected Topics in Power Electronics     Hybrid Journal   (Followers: 53)
IEEE Journal of the Electron Devices Society     Open Access   (Followers: 9)
IEEE Journal on Exploratory Solid-State Computational Devices and Circuits     Hybrid Journal   (Followers: 1)
IEEE Letters on Electromagnetic Compatibility Practice and Applications     Hybrid Journal   (Followers: 4)
IEEE Magnetics Letters     Hybrid Journal   (Followers: 7)
IEEE Nanotechnology Magazine     Hybrid Journal   (Followers: 42)
IEEE Open Journal of Circuits and Systems     Open Access   (Followers: 3)
IEEE Open Journal of Industry Applications     Open Access   (Followers: 3)
IEEE Open Journal of the Industrial Electronics Society     Open Access   (Followers: 3)
IEEE Power Electronics Magazine     Full-text available via subscription   (Followers: 80)
IEEE Pulse     Hybrid Journal   (Followers: 5)
IEEE Reviews in Biomedical Engineering     Hybrid Journal   (Followers: 23)
IEEE Solid-State Circuits Letters     Hybrid Journal   (Followers: 3)
IEEE Solid-State Circuits Magazine     Hybrid Journal   (Followers: 13)
IEEE Transactions on Aerospace and Electronic Systems     Hybrid Journal   (Followers: 384)
IEEE Transactions on Antennas and Propagation     Full-text available via subscription   (Followers: 77)
IEEE Transactions on Automatic Control     Hybrid Journal   (Followers: 66)
IEEE Transactions on Autonomous Mental Development     Hybrid Journal   (Followers: 8)
IEEE Transactions on Biomedical Engineering     Hybrid Journal   (Followers: 40)
IEEE Transactions on Broadcasting     Hybrid Journal   (Followers: 13)
IEEE Transactions on Circuits and Systems for Video Technology     Hybrid Journal   (Followers: 27)
IEEE Transactions on Consumer Electronics     Hybrid Journal   (Followers: 45)
IEEE Transactions on Electron Devices     Hybrid Journal   (Followers: 18)
IEEE Transactions on Geoscience and Remote Sensing     Hybrid Journal   (Followers: 232)
IEEE Transactions on Haptics     Hybrid Journal   (Followers: 6)
IEEE Transactions on Industrial Electronics     Hybrid Journal   (Followers: 75)
IEEE Transactions on Industry Applications     Hybrid Journal   (Followers: 46)
IEEE Transactions on Information Theory     Hybrid Journal   (Followers: 27)
IEEE Transactions on Learning Technologies     Full-text available via subscription   (Followers: 12)
IEEE Transactions on Power Electronics     Hybrid Journal   (Followers: 82)
IEEE Transactions on Services Computing     Hybrid Journal   (Followers: 4)
IEEE Transactions on Signal and Information Processing over Networks     Hybrid Journal   (Followers: 14)
IEEE Transactions on Software Engineering     Hybrid Journal   (Followers: 82)
IEEE Women in Engineering Magazine     Hybrid Journal   (Followers: 11)
IEEE/OSA Journal of Optical Communications and Networking     Hybrid Journal   (Followers: 16)
IEICE - Transactions on Electronics     Full-text available via subscription   (Followers: 11)
IEICE - Transactions on Information and Systems     Full-text available via subscription   (Followers: 5)
IET Cyber-Physical Systems : Theory & Applications     Open Access   (Followers: 1)
IET Energy Systems Integration     Open Access   (Followers: 1)
IET Microwaves, Antennas & Propagation     Hybrid Journal   (Followers: 38)
IET Nanodielectrics     Open Access  
IET Power Electronics     Hybrid Journal   (Followers: 62)
IET Smart Grid     Open Access   (Followers: 1)
IET Wireless Sensor Systems     Hybrid Journal   (Followers: 18)
IETE Journal of Education     Open Access   (Followers: 3)
IETE Journal of Research     Open Access   (Followers: 10)
IETE Technical Review     Open Access   (Followers: 12)
IJEIS (Indonesian Journal of Electronics and Instrumentation Systems)     Open Access   (Followers: 3)
Industrial Technology Research Journal Phranakhon Rajabhat University     Open Access  
Informatik-Spektrum     Hybrid Journal   (Followers: 2)
Instabilities in Silicon Devices     Full-text available via subscription   (Followers: 1)
Intelligent Transportation Systems Magazine, IEEE     Full-text available via subscription   (Followers: 14)
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: 12)
International Journal of Antennas and Propagation     Open Access   (Followers: 13)
International Journal of Applied Electronics in Physics & Robotics     Open Access   (Followers: 4)
International Journal of Computational Vision and Robotics     Hybrid Journal   (Followers: 5)
International Journal of Control     Hybrid Journal   (Followers: 11)
International Journal of Electronics     Hybrid Journal   (Followers: 6)
International Journal of Electronics and Telecommunications     Open Access   (Followers: 13)
International Journal of Granular Computing, Rough Sets and Intelligent Systems     Hybrid Journal   (Followers: 3)
International Journal of High Speed Electronics and Systems     Hybrid Journal  
International Journal of Hybrid Intelligence     Hybrid Journal  
International Journal of Image, Graphics and Signal Processing     Open Access   (Followers: 17)
International Journal of Microwave and Wireless Technologies     Hybrid Journal   (Followers: 11)
International Journal of Nano Devices, Sensors and Systems     Open Access   (Followers: 14)
International Journal of Nanoscience     Hybrid Journal   (Followers: 1)
International Journal of Numerical Modelling: Electronic Networks, Devices and Fields     Hybrid Journal   (Followers: 4)
International Journal of Power Electronics     Hybrid Journal   (Followers: 26)
International Journal of Review in Electronics & Communication Engineering     Open Access   (Followers: 4)
International Journal of Sensors, Wireless Communications and Control     Hybrid Journal   (Followers: 12)
International Journal of Systems, Control and Communications     Hybrid Journal   (Followers: 4)
International Journal of Wireless and Microwave Technologies     Open Access   (Followers: 8)
International Transaction of Electrical and Computer Engineers System     Open Access   (Followers: 2)
JAREE (Journal on Advanced Research in Electrical Engineering)     Open Access  
Journal of Biosensors & Bioelectronics     Open Access   (Followers: 4)
Journal of Advanced Dielectrics     Open Access   (Followers: 1)
Journal of Artificial Intelligence     Open Access   (Followers: 14)
Journal of Circuits, Systems, and Computers     Hybrid Journal   (Followers: 4)
Journal of Computational Intelligence and Electronic Systems     Full-text available via subscription   (Followers: 1)
Journal of Electrical and Electronics Engineering Research     Open Access   (Followers: 39)
Journal of Electrical Bioimpedance     Open Access   (Followers: 2)
Journal of Electrical Bioimpedance     Open Access  
Journal of Electrical Engineering & Electronic Technology     Hybrid Journal   (Followers: 7)
Journal of Electrical, Electronics and Informatics     Open Access  
Journal of Electromagnetic Analysis and Applications     Open Access   (Followers: 8)
Journal of Electromagnetic Waves and Applications     Hybrid Journal   (Followers: 9)
Journal of Electronic Design Technology     Full-text available via subscription   (Followers: 6)
Journal of Electronic Science and Technology     Open Access   (Followers: 1)
Journal of Electronics (China)     Hybrid Journal   (Followers: 5)
Journal of Energy Storage     Full-text available via subscription   (Followers: 5)
Journal of Engineered Fibers and Fabrics     Open Access   (Followers: 2)
Journal of Field Robotics     Hybrid Journal   (Followers: 4)
Journal of Guidance, Control, and Dynamics     Hybrid Journal   (Followers: 204)
Journal of Information and Telecommunication     Open Access   (Followers: 1)
Journal of Intelligent Procedures in Electrical Technology     Open Access   (Followers: 3)
Journal of Low Power Electronics     Full-text available via subscription   (Followers: 10)
Journal of Low Power Electronics and Applications     Open Access   (Followers: 10)
Journal of Microelectronics and Electronic Packaging     Hybrid Journal   (Followers: 1)
Journal of Microwave Power and Electromagnetic Energy     Hybrid Journal   (Followers: 4)
Journal of Microwaves, Optoelectronics and Electromagnetic Applications     Open Access   (Followers: 10)
Journal of Nuclear Cardiology     Hybrid Journal  
Journal of Optoelectronics Engineering     Open Access   (Followers: 4)
Journal of Physics B: Atomic, Molecular and Optical Physics     Hybrid Journal   (Followers: 32)
Journal of Power Electronics     Hybrid Journal   (Followers: 3)
Journal of Power Electronics & Power Systems     Full-text available via subscription   (Followers: 12)
Journal of Semiconductors     Full-text available via subscription   (Followers: 5)
Journal of Sensors     Open Access   (Followers: 27)
Journal of Signal and Information Processing     Open Access   (Followers: 8)
Jurnal ELTIKOM : Jurnal Teknik Elektro, Teknologi Informasi dan Komputer     Open Access  
Jurnal Rekayasa Elektrika     Open Access  
Jurnal Teknik Elektro     Open Access  
Jurnal Teknologi Elektro     Open Access  
Kinetik : Game Technology, Information System, Computer Network, Computing, Electronics, and Control     Open Access   (Followers: 1)
Majalah Ilmiah Teknologi Elektro : Journal of Electrical Technology     Open Access   (Followers: 2)
Metrology and Measurement Systems     Open Access   (Followers: 6)
Microelectronics and Solid State Electronics     Open Access   (Followers: 28)
Nanotechnology, Science and Applications     Open Access   (Followers: 6)
Nature Electronics     Hybrid Journal   (Followers: 2)
Networks: an International Journal     Hybrid Journal   (Followers: 4)
Open Electrical & Electronic Engineering Journal     Open Access  
Open Journal of Antennas and Propagation     Open Access   (Followers: 9)
Paladyn. Journal of Behavioral Robotics     Open Access   (Followers: 1)
Power Electronics and Drives     Open Access   (Followers: 2)
Problemy Peredachi Informatsii     Full-text available via subscription  
Progress in Quantum Electronics     Full-text available via subscription   (Followers: 8)
Radiophysics and Quantum Electronics     Hybrid Journal   (Followers: 2)
Recent Advances in Communications and Networking Technology     Hybrid Journal   (Followers: 3)
Recent Advances in Electrical & Electronic Engineering     Hybrid Journal   (Followers: 11)
Research & Reviews : Journal of Embedded System & Applications     Full-text available via subscription   (Followers: 6)
Revue Méditerranéenne des Télécommunications     Open Access   (Followers: 1)
Security and Communication Networks     Hybrid Journal   (Followers: 2)
Selected Topics in Applied Earth Observations and Remote Sensing, IEEE Journal of     Hybrid Journal   (Followers: 57)
Semiconductors and Semimetals     Full-text available via subscription   (Followers: 1)
Sensing and Imaging : An International Journal     Hybrid Journal   (Followers: 2)
Solid State Electronics Letters     Open Access  
Solid-State Electronics     Hybrid Journal   (Followers: 9)
Superconductor Science and Technology     Hybrid Journal   (Followers: 3)
Synthesis Lectures on Power Electronics     Full-text available via subscription   (Followers: 3)
Technical Report Electronics and Computer Engineering     Open Access  
TELE     Open Access  
Telematique     Open Access  
TELKOMNIKA (Telecommunication, Computing, Electronics and Control)     Open Access   (Followers: 11)
Transactions on Cryptographic Hardware and Embedded Systems     Open Access   (Followers: 4)

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Similar Journals
Journal Cover
IEEE Transactions on Industrial Electronics
Journal Prestige (SJR): 2.192
Citation Impact (citeScore): 9
Number of Followers: 75  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0278-0046
Published by IEEE Homepage  [229 journals]
  • IEEE Industrial Electronics Society
    • Abstract: Presents a listing of the editorial board, board of governors, current staff, committee members, and/or society editors for this issue of the publication.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • IEEE Industrial Electronics Society
    • Abstract: Presents a listing of the editorial board, board of governors, current staff, committee members, and/or society editors for this issue of the publication.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Information for Authors
    • Abstract: These instructions give guidelines for preparing papers for this publication. Presents information for authors publishing in this journal.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • A Multicell Network Control and Design for Three-Phase Grid-Connected
           Inverter
    • Pages: 2740 - 2749
      Abstract: Three-phase grid-connected inverter with the LCL filter is commonly controlled in synchronous frame in order to independently control active power and reactive power. And proportional-integral controller is usually adopted in synchronous frame to achieve zero steady error of inverter fundamental current. However, d–q axes cross-coupling issue may deteriorate the dynamic and steady-state performance. Moreover, the weak damping characteristic of the LCL filter will lead to resonance issue. Both issues are analyzed by the established complex-vector model of the inverter in this article. A novel multicell network control structure is proposed to address both coupling and resonance problems. To design all parameters of the multicell network controller, a multiple parameter design method is proposed. Moreover, this design method can adapt to weak grid well. Based on the proposed control structure and design method, d–q axes cross-coupling issue can be addressed thoroughly, and the damping performance is also improved obviously. Besides, the excellent steady-state and dynamic performances are realized simultaneously. Finally, the superior performances of the proposed control are verified by simulation and experimental results.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • A Single DC Source-Based Three-Level Inverter Topology for a Four-Pole
           Open-End Winding Nine-Phase PPMIM Drives
    • Pages: 2750 - 2759
      Abstract: This article proposes a three-level inverter topology for nine-phase pole phase-modulated induction motor (PPMIM) drives by using the two identical voltage profile coils (IVPC) of a four-pole stator winding. In general, the two IVPCs of each phase winding are connected in series, but in this article, these two IVPCs are separated and excited with conventional two-switch inverter legs without disturbing the flux per pole and other machine parameters. The 18 IVPCs of four-pole nine-phase induction motor (IM) are excited with 18 two-switch inverter legs and fed by the same dc source. Each two-switch inverter leg generates the two-level voltage across each IVPC winding, i.e., the resultant voltage seen by the phase winding is a three-level voltage waveform. As compared to conventional nine-phase neutral point and flying capacitor multilevel inverters (MLIs), the requirement of the dc-link magnitude for the proposed topology is reduced by 50%. The nine-phase PPMIM drive is modulated with the carrier-based three-phase space vector pulsewidth modulation in order to enhance the linear modulation range (LMR). The inverter legs associated with two IVPCs per phase in 9-phase 4-pole (9PH-4PO) mode and six IVPCs per phase in 3-phase 12-pole (3PH-12PO) mode are modulated with the same reference wave and phase-displaced triangular waves. This results in the generation of multilevel voltage with improved harmonic voltage profile, i.e., minimizes the torque pulsations of nine-phase PPMIM drive. The validation of the proposed MLI-fed 5 hp nine-phase PPMIM drive is carried out by using the Ansys Maxwell FEM tool as well as with an experimental prototype.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • A Centralized CB-MPC to Suppress Low-Frequency ZSCC in Modular Parallel
           Converters
    • Pages: 2760 - 2771
      Abstract: The parallel operation of three-phase converters has become an effective way to achieve modularity. However, zero-sequence circulating current (ZSCC) will appear when the multiparalleled converter modules share a common dc link. In the event that the converters have different output powers and inevitable circuit parameter mismatch, low-frequency (LF) ZSCC can be produced. To address the LF-ZSCC issues, in this article, we propose a centralized carrier-based model predictive control (CB-MPC) scheme for modular parallel converters. This control scheme can be implemented either in master converters or in a dedicate central controller. The CB-MPC can achieve both power control and LF-ZSCC elimination. In addition, with carriers adopted, interleaving and fixed device switching frequency can be easily realized. As such, the benefits of model predictive control and interleaving can be combined. Based on the ZSCC model derived in this article, the elimination of LF-ZSCC can be achieved for more than two paralleled converters when they have different output powers and/or with parameter mismatch. The effectiveness of the proposed CB-MPC has been verified by the simulation and experimental results.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Optimal Third-Harmonic Current Injection for Asymmetrical Multiphase
           Permanent Magnet Synchronous Machines
    • Pages: 2772 - 2783
      Abstract: This article proposes a modeling approach and an optimization strategy to exploit a third-harmonic current injection for the torque enhancement in multiphase isotropic permanent magnet synchronous machines with nonsinusoidal back electromotive forces. The modeling approach is based on a proper vector space decomposition and on the associated rotational transformation, aimed to properly select a set of stator current space vectors to be controlled. It is presented for a generic (i.e., asymmetrical, with an arbitrary angular shift) winding configuration. The injection strategy is related to the choice of a constant synchronous current set aimed at minimizing the average stator winding losses for a given reference torque by using the first and the third spatial harmonics of the air-gap flux density. The optimal solution has been found analytically and has been developed in detail for a selected set of asymmetrical winding configurations. Both the numerical and experimental results are in good agreement with the theoretical analysis.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • An Improved Fault-Tolerant Control Scheme for Cascaded H-Bridge STATCOM
           With Higher Attainable Balanced Line-to-Line Voltages
    • Pages: 2784 - 2797
      Abstract: Fault-tolerant operation ability is of great importance for stable operation of cascaded H-bridge (CHB) converters, under open-circuit (OC) or short-circuit (SC) switch failures in submodule (SM). In this article, an improved fault-tolerant control strategy is proposed for CHB-based static synchronous compensator (STATCOM) under SM faults. First of all, compared with the conventional fault-tolerant method of directly bypassing the faulty SMs, the proposed fault-tolerant method takes advantage of the healthy switches of the faulty SMs, where they are still able to generate either positive or negative voltage level. As a result, more output voltage levels can be generated, and it raises the attainable balanced line-to-line voltage, especially when different fault types exist at the same time. Then, based on the specific condition of OC fault or SC fault, when the output voltage reference of the faulty phase reaches its limit, the references of the other two healthy phases are redistributed to generate the desired line-to-line voltage. With the reconfiguration of modulation waves, the attainable balanced line-to-line voltage can be further improved. In addition, the proposed fault-tolerant method possesses the ability of cluster voltage balancing, which is an important issue for the STATCOM application. Simulation and experimental results validate the effectiveness of the proposed fault-tolerant method.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Circulating Current Optimization Control of MMC
    • Pages: 2798 - 2811
      Abstract: Modular multilevel converter (MMC) is a preferred topology for higher power applications. The instantaneous voltage mismatch between the phase legs and dc bus in MMC leads to predominantly second-harmonic circulating current (CC). The sizes of submodule (SM) capacitor and arm inductor, power losses and current rating of semiconductor switches in MMC are influenced by the CC. This article proposes a circulating current optimization control (CCOC) scheme for MMC, which reduces the arm current peak value without increasing the SMs capacitors size for the same maximum voltage ripples. It enables the MMC to handle more power with the same rated switches. This controller works on the principle of controlling the amplitude and phase angle of CC to follow their respective optimized references. A detailed design and implementation method of CCOC is presented for all possible operating conditions of MMC in terms of modulation indices and load power factors. A comparative evaluation performed between CCOC and other major CC control schemes highlights its main features. The efficacy of the proposed scheme is validated using simulations and also using experimental studies on a seven-level three-phase grid-connected MMC prototype. The results demonstrate the effectiveness of the CCOC scheme and verify the proposed principles.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Current-Modulation-Based On-Line Resonance Tuning Strategy for Linear
           Generator Drives
    • Pages: 2812 - 2822
      Abstract: Linear generators (LGs) are frequently used for energy harvesting with free-piston Stirling engines, thermoacoustic engines, and wave energy converters. This article presents a control strategy to track and maintain LG resonance conditions in real time. The algorithm is based on the LG response to a low-frequency amplitude modulation of the current component in phase with the instantaneous position (d-axis). The averaged product of modulated air-gap power and modulation signal is fed into a controller to adjust the d-axis current and restore resonance. The use of air-gap power instead of dc power improves resonance tracking accuracy and eliminates steady-state low-frequency stroke oscillations. This article presents a full theoretical analysis providing accurate steady-state and small-signal models for control synthesis. The broad experimental validation included in the article proves that the control is able to restore resonance even when the force-source introduces significant additional mechanical impedance.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Dynamic Performance Improvement for Permanent Magnet Generator System
           Using Current Compensating Method With Two-Degrees-of-Freedom Control
    • Pages: 2823 - 2833
      Abstract: This article proposes a two-degrees-of-freedom (TDOF) control with torque current compensating method (TCCM) to enhance the dynamic performance of permanent magnet generator (PMG) system when load changes. First, the mathematic model of PMG system with active front-end rectifier is introduced. Based on the system model, the proportional–integral controller of current loop is designed, and the TDOF controller designed with internal model control principle is derived for voltage loop control. There are two sets of parameters in the TDOF controller, one is used to regulate the system tracking performance when the command dc-link voltage changes, and the other is used to regulate the system antidisturbance capability when the electrical load changes. Second, the TCCM is proposed to further improve the system dynamic performance. The variation of torque current is applied to revise the command dc-link voltage, namely, the command dc-link voltage increases under loading occasion and decreases when unload occurs. The TCCM needs no additional hardware and is simple to implement. Simulation and experimental results verify the effectiveness of the proposed method.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Integration of Battery Charging Process for EVs Into Segmented Three-Phase
           Motor Drive With V2G-Mode Capability
    • Pages: 2834 - 2844
      Abstract: The integration of nine-phase permanent magnet synchronous machines (nine-phase PMSMs), employed in on-board integrated battery charger for electric vehicles (EVs), into three-phase grid generates an inevitable torque fluctuation in charging and vehicles to grid (V2G) modes. This undesirable torque, which is the source of motor vibration and noise, is due to the interaction among the zero-sequence current, triplen harmonics (third and ninth) of induced back electromotive force, and rotor position. In this article, a new solution for nine-winding integrated battery chargers of EVs is considered. A segmented three-phase PMSM with nine windings is used to replace the nine-phase PMSMs. With this configuration, the system has the advantage of torque-free in charging/V2G mode, low core loss, and simple control (based on the three-phase control) in both traction and charging/V2G modes, with the privilege of employing the reduced number of sensor and with no additional new elements. Through proper three-phase control strategy, the system operates under unity power factor with total harmonic distortion below 5%. Control strategies for charging, V2G, and motoring are given; moreover, the simulation and experimental results are provided to validate the theoretical analysis.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Modulation Method for Nine-Switch Converter Based on Equivalent Mechanism
           Between Nine-Switch Converter and Dual Six-Switch Converters
    • Pages: 2845 - 2855
      Abstract: In this article, the equivalent mechanism between nine-switch converter (NSC) and the two six-switch converters (SSCs) is explained in detail. In order to achieve the decoupling of the upper and lower ac terminals, the concept of virtual leg is proposed and the decoupling model of NSC is established based on virtual legs. In this model, the NSC is equivalent to dual constrained SSCs. Continually, the space vector modulation method of NSC is proposed based on dual constrained SSCs modulation for both common frequency and different frequency modes. In the proposed modulation method, the concept of space vector distance function (SVDF) is proposed. SVDF represents the actual switching times between any two actual working states of NSC. The closer distance between the two actual states is, the smaller the actual switching loss will be. Using the modulation method, the NSC can realize the independent control of two sets of three-phase ac voltage and achieve the same control performance as the dual SSCs. The validity of the proposed converter is verified through simulations and experiments.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • General Formulation of Kalman-Filter-Based Online Parameter Identification
           Methods for VSI-Fed PMSM
    • Pages: 2856 - 2864
      Abstract: This article proposes two Kalman-filter-based online identification schemes for permanent magnet synchronous machines (PMSMs), where the nonlinearity of a voltage-source inverter (VSI) is taken into account. One is formulated from an extended Kalman filter; the other uses a dual extended Kalman filter. They are generally formulated and can be applied to any identifiable electrical parameter combinations. The proposed schemes are further implemented on an industrial embedded control system. Their performance tests are conducted on a PMSM under static and dynamic conditions and compared with the extended Kalman filter without VSI nonlinearity compensation. The effectiveness of the proposed approaches is proved by the experimental results. Furthermore, a sensitivity analysis of the initial setup of parameter estimates has shown that the proposed estimators are robust against poor initial value choices. Real-time feasibility of the proposed estimators up to $text{20};text{kHz}$ is demonstrated via experiments.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Estimation Procedure Based on Less Filtering and Robust Tracking for a
           Self-Sensing Control of IPMSM
    • Pages: 2865 - 2875
      Abstract: For the self-sensing control of interior permanent magnet synchronous motors (IPMSM), the rotor position and speed estimation based on high-frequency (HF) injection techniques generally employs two parts after the signal injection: signal processing/heterodyning process and tracking. This article proposes significant improvements for these two parts. First, the low-pass filters used in the classical heterodyning process of HF injection techniques are removed, which leads to the proposal of a novel heterodyning process in order to improve the estimation procedure in terms of delays, cost/complexity of implementation, and harmonics. Second, an independent machine parameters estimation based on step-by-step sliding mode observer using only the sign of the rotor position estimation error is developed. Thanks to this observer, the tuning of position, speed, and acceleration observer gains is achieved in a decoupled manner, which ensures states convergence separately in finite time. Third, the machine acceleration is estimated to improve the estimation procedure in transient modes. These contributions enhance significantly the estimation procedure in all operating ranges. A comparative study of the robustness/performance of the proposed strategy and classical tracking algorithms is carried out. Both simulations and experimental tests on an IPMSM rig are conducted in the framework of electric propulsion benchmark used in automotive applications, showing good agreement with the expected results.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Design and Analysis of Oil-Immersed Cooling Stator With Nonoverlapping
           Concentrated Winding for High-Power Ironless Stator Axial-Flux Permanent
           Magnet Machines
    • Pages: 2876 - 2886
      Abstract: Ironless stator axial-flux permanent magnet (AFPM) machines provide many attractive electromagnetic performances such as high efficiency in high-frequency mode and strong short-term overload ability, which make them more competitive in flywheel energy storage applications. However, designing high-torque-density AFPM machines, particularly their ironless stators, is with significant challenges and needs great efforts. In this article, a high-strength oil-immersed cooling stator with nonoverlapping concentrated winding is proposed for high-power ironless stator AFPM machine applications. This article explains in detail the design, analysis, and manufacturing process of the proposed oil-immersed cooling stator. With the three-dimensional finite-element analysis (3-D FEA), a 9000-r/m/50-kW 12-slot/10-pole prototype for a flywheel energy storage system is successfully designed and developed using the proposed high-strength oil-immersed cooling ironless stator. The experimental test results demonstrate the effectiveness of the cooling design and mechanical strength.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Analysis and Design of a PM-Assisted Wound Rotor Synchronous Machine With
           Reluctance Torque Enhancement
    • Pages: 2887 - 2897
      Abstract: In this article, a novel structure is proposed for a wound rotor synchronous machine with a small ferrite magnet in each rotor pole. The key is to achieve a higher reluctance torque term and also acquire torque-angle approaching that would allow the field torque and reluctance torque to reach maximum values at the closed current phase angle for efficient production of the average total torque. The assisting ferrite magnet in the proposed model helps compensate the q-axis flux while keeping the d-axis flux unchanged as much as possible, for enhancing reluctance torque and power factor. Meanwhile, the assisting ferrite magnet makes an asymmetrical magnetic flux distribution to close the current phase angles between the maximum of the field torque and the reluctance torque. Moreover, the related parameters of the assisting ferrite magnet in the proposed structure were determined by optimal techniques using the Kriging method and genetic algorithm. In addition, the potential for demagnetization of the assisting magnet was analyzed and the results verified that this would not affect the motor output performance. Finally, prototypes are manufactured for the experiments to verify the principle analysis and finite element analysis results.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Phase Reconfiguring Technique for Enhancing the Modulation Index of
           Multilevel Inverter Fed Nine-Phase IM Drive
    • Pages: 2898 - 2906
      Abstract: In this article, a multilevel inverter (MLI) scheme is proposed for four-pole (4-pole), nine-phase (9-phase) induction motor (IM) drives with improved dc bus utilization as well as reduced device count. The proposed MLI is realized with nine three-switch inverter legs (3-SIL) and a single dc source. In the proposed MLI, each 3-SIL is utilized for exciting the two identical voltage profile coils/phase of the four-pole (4-pole) stator winding, which means each leg has to be modulated with two references. These two independent references/leg will limit the modulation index (M.I) of 3-SIL-based proposed MLI. This lower M.I will result in a requirement of the higher magnitude of dc-link voltage to achieve the rated load voltage requirement. In this article, an effective phase reconfiguring concept is proposed for reducing the dc-link voltage requirement of the proposed MLI. In addition, all the possibilities of phase reconfiguring details for proposed MLI-fed 9-phase IM drive are also presented. A three-phase carrier-based space vector pulsewidth modulation is implemented for improving the linear modulation range of proposed MLI configuration further. In contrast with existing 9-phase three-level inverters, like NPC and FC, the proposed MLI configuration requires only one dc link (with half of the magnitude) and lesser number of semiconductor devices. The proposed MLI-fed, 5 hp, 9-phase, 4-pole IM drive is validated by using Ansys Maxwell FEM simulation and experimental prototype for entire modulation range.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • No-Load Performance Analysis of an Asymmetric-Pole Single-Phase Doubly
           Salient Permanent Magnet Machine
    • Pages: 2907 - 2918
      Abstract: Asymmetric-pole single-phase doubly salient permanent magnet machine (APSP-DSPMM) can yield higher torque and lower dead zone than the traditional one. Some special structural factors, such as the stator pole pieces, unequal air-gap lengths, and seriously saturated auxiliary teeth, if not properly considered, may bring large errors in the electromagnetic performance evaluation. This article proposes an improved magnetomotive force-specific permeance method to account for these special structural factors. This method is implemented numerically to obtain the electromagnetic performance of APSP-DSPMM under the conditions of no-load and full-load, and the results are compared with those of the two-dimensional finite-element analysis. The theoretical results are verified by the experimental test results of a prototype.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Thermal Model Approach to Multisector Three-Phase Electrical Machines
    • Pages: 2919 - 2930
      Abstract: Multisector machines reveal a high fault-tolerant capability, since failure events can be isolated by de-energizing the faulty sector, while the healthy ones contribute in delivering the required power. This article is focused on the thermal analysis of multisector three-phase machines in healthy and faulty operations. First, a 3-D lumped parameter thermal network (LPTN) of a single sector is developed and finetuned against experimental data, through a genetic algorithm for identifying the uncertain parameters. According to the operating conditions, the varying housing surface temperature affects the heat exchanged to the ambient. Hence, an analytical formula is proposed to adjust the natural convection coefficient value depending on the operating condition. Then, the 3-D LPTN, modeling the whole machine, is built aiming at investigating the thermal behavior during faulty conditions. Finally, the complete 3-D LPTN is employed for predicting the machine thermal performance under several faulty conditions. Furthermore, the current overload experienced by the healthy sector (in order to keep the same torque level as during the pre-fault operation) is determined, in accordance with the magnet wire thermal class. The effectiveness of the 3-D LPTN in predicting the temperature is experimentally demonstrated.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Iron Loss Modeling in Dual Stator Winding Induction Machines With Unequal
           Pole Pairs and Squirrel Cage Rotor
    • Pages: 2931 - 2941
      Abstract: This article pertains to dual stator winding induction machines (DSWIMs) modeling and proposes an equivalent electrical circuit for DSWIMs that considers the iron loss effect. It is proved that the iron loss in DSWIMs is comprised of two independent parts resulting from their winding sets. Accordingly, the proposed model is comprised of two distinct parts and it is based on the assumption of independent operation of DSWIM winding sets. This model is valid in dynamic and steady-state operation conditions. The dq0 form of the proposed model is derived in an arbitrary reference frame. In addition, based on this model the iron loss estimation in DSWIMs is presented. The proposed model is simulated in MATLAB/Simulink based on the parameters obtained from IEEE standard characterization tests performed on a 3.3-kW DSWIM and also some experimental tests are executed via a digital signal processor (DSP)-based DSWIM drive system. Comparison of the simulation and experimental results confirms the validity of the proposed model both in steady-state and transient conditions. Moreover, this comparison clarifies that the proposed iron loss estimation method can account for the iron loss with high accuracy.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Self-Calibration of Phase Current Sensors With Sampling Errors by
           Multipoint Sampling of Current Values in a Single PWM Cycle
    • Pages: 2942 - 2951
      Abstract: The accuracy of current sensors is most crucial for the performance of an interior permanent magnet synchronous motor (IPMSM) drive. However, it may have sampling errors that are unavoidable for an actual drive. Therefore, to cope with this problem, in this article, a self-calibration strategy for phase-current sensors is proposed by utilizing the proposed topology and the correlation among the multiple current values obtained by current sampling values during one single pulsewidth modulation cycle, making minor changes for the cablings of the conventional current sensors in the premise of not affecting the normal operation of the drive, and abandoning complex observers or filters for easing the computational burden. Besides, its effectiveness was verified by the experimental results on a 5-kW IPMSM motor prototype, which showed that such sampling errors could be well estimated and eliminated.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Online Fault Diagnosis for Rotating Rectifier in Wound-Rotor Synchronous
           Starter–Generator Based on Geometric Features of Current Trajectory
    • Pages: 2952 - 2963
      Abstract: Accurate and timely fault diagnosis of the rotating rectifier in wound-rotor synchronous starter–generator (WRSSG) plays an important role in improving the reliability of the WRSSG system. By analyzing the geometric features of the rotor current trajectory of the main exciter (ME) under health and different fault conditions of the rotating rectifier, in this article, a fault diagnosis method for the rotating rectifier based on the geometric features of ME rotor current trajectory is proposed. In this method, ME rotor currents are estimated first, and then the center distance, center angle, and length–width ratio of the ME rotor current trajectory are calculated and used to detect fault occurrence, locate the faulty diode, and identify the fault type for the rotating rectifier, respectively. The experimental results verified the feasibility and effectiveness of the proposed fault diagnosis method.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • A Novel Sensorless Initial Position Estimation and Startup Method
    • Pages: 2964 - 2975
      Abstract: In this article, a low noise and simple initial position estimation and startup method based on high-frequency rotating sinusoidal voltage injection is proposed for interior permanent magnet synchronous machine. Different from the conventional method that uses negative sequence current and closed-loop position observer, the proposed method simply compares the three-phase high-frequency current amplitudes calculated by discrete Fourier transform to detect the rotor sector. The initial position can be obtained within only half of the injection cycle without parameter tuning. Thus, it is fast and simple compared to the conventional method. Both discrete and continuous rotor positions can be obtained and used for startup. Furthermore, to mitigate the acoustic noise during starting, a multifrequency injection strategy is introduced to reduce the noise emission caused by high-frequency voltage injection. Experiments are carried out to verify the effectiveness of the proposed method.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Model Predictive Direct Duty-Cycle Control for PMSM Drive Systems With
           Variable Control Set
    • Pages: 2976 - 2987
      Abstract: Finite control set model predictive control has received extensive attention because of its excellent dynamic performance; however, it still needs to be studied in terms of torque ripples reduction and parameter robustness. To reduce the steady-state torque ripples and maintain the appropriate antiparameter perturbation ability, in this article, we propose a model predictive direct duty-cycle control (MPD2C) strategy based on “variable control set (VCS).” In the proposed strategy, the direct mapping relations between the electromagnetic torque, flux, and three-phase duty cycles have been established by exploring the dual relationship of vector synthesis and duty cycles. On this basis, the novel predictive model and VCS that uses the three-phase duty cycles as the key variable are constructed. Finally, the proposed strategy determines the three-phase duty cycles from VCS by employing a two-stage optimization mechanism, which means the proposed strategy can generate virtual vectors with multiple insulated gate bipolar transistor (IGBT) switching patterns. Then, the high-precision torque and flux adjustment would be achieved. The experimental results show that VCS-MPD2C has excellent static and dynamic control performance, acceptable execution efficiency, and relatively good parameter robustness.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Effect of Phase Shift Angle on Radial Force and Vibration Behavior in Dual
           Three-Phase PMSM
    • Pages: 2988 - 2998
      Abstract: This article investigates the effect of phase shift angle on radial force and vibration behavior in the dual three-phase permanent magnet (PM) synchronous motor (DTP-PMSM). First, the elimination principles of stator magneto-motive force and radial force harmonics with different phase shift angles are derived. Afterward, a 48-slot/22-pole DTP-PMSM with appropriate windings configurations are analyzed from the perspectives of the electromagnetic performance and vibration behavior in detail. It is found that the 7.5° and 30° configurations have great significance for reducing the amplitude of radial force harmonics. The 7.5° configuration has the lowest second-order radial force amplitude, while the 30° configuration has the smallest amplitude of fourth-, sixth-, and eighth-order radial forces. According to the results calculated by the multiphysics vibration prediction model, the 30° configuration has lower vibration acceleration in the entire frequency band. Finally, the prototypes of the 48-slot/22-pole DTP-PMSMs with 30° and 60° phase shift angle are fabricated. The tests are conducted to validate the theoretical analysis.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Analysis of a Spoke-Array Brushless Dual-Electrical-Port
           Dual-Mechanical-Port Machine With Reluctance Rotor
    • Pages: 2999 - 3011
      Abstract: A novel brushless dual-electrical-port dual-mechanical-port (BLDD) machine, with spoke-array permanent magnet (PM) outer rotor and reluctance inner rotor is proposed in this article. The BLDD machine can be regarded as the combination of the flux modulation machine and PM synchronous machine (PMSM). Compared to the existing BLDD machine, the PMs of the proposed machine only insert into the outer rotor, hence both torques in two machines can reach their optimal values at the same time. Moreover, the spoke-array PMs with inherent flux-focusing effect can reduce the effective air-gap length of PMSM portion and improve the working flux density, thus increasing the torque density significantly. Besides, the reluctance inner rotor without magnets has the advantages of simple structure and high reliability. The structure and operation principle are introduced. Then, the influences of main parameters including slot/pole combination, split ratio, PM size on torque performance are studied. Next, the proposed BLDD PM machine is compared with the conventional one in terms of air-gap flux density, back electromotive force, magnetic forces, and torque performances. A prototype and test bed are designed and built, and the experimental results verify the analysis results.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • A Soft-Switching Current-Source-Inverter-Fed Motor Drive With Reduced
           Common-Mode Voltage
    • Pages: 3012 - 3021
      Abstract: This article proposes a common-mode voltage (CMV) attenuation method for the three-phase current source inverter (CSI)-fed permanent-magnet synchronous machine drive. The key of this method is to introduce an auxiliary circuit branch connected in parallel with the dc link. Based on the dedicated switching strategy, the zero-voltage-switching conditions are provided for the main switches in the CSI. In particular, the zero current vector is newly constructed without utilizing shoot-through operation in the CSI. Thus, the CMV in the traditional CSI drives is attenuated significantly. Compared with the existing research on CMV suppression, the proposed method will not compromise the modulation index range or increase output current harmonics. Meanwhile, the overshoot voltage can be clamped by the auxiliary power circuit in the dc link under open-circuit fault in the power switches. The system configuration, operating principle, analysis of operation modes, as well as the control scheme are described in detail. Both simulation and experimental results are presented to verify the performance of the proposed method.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • A Brushless Dual-Electrical-Port Dual-Mechanical-Port Machine With
           Integrated Winding Configuration
    • Pages: 3022 - 3032
      Abstract: The brushless dual-electrical-port dual-mech-anical-port (BLDD) machine is a newly developed machine type which can replace conventional power split system based on planetary gear. BLDD machine always contains one stator and two coaxial rotors, and two sets of windings are required to control two rotors. In this article, a novel integrated winding configuration is proposed to replace two original windings with different pole number, i.e., the integrated winding should have the ability to produce two pole number, independent-control magnetomotive forces (MMFs). By carefully designing coil displacement and terminal configuration, two current components with different phases are skillfully injected to the integrated winding, which produces MMFs with different pole-pairs. Compared with original winding configuration, the proposed integrated winding has two main advantages. First, higher current can be injected under the same copper loss, which improves the torque density of BLDD machine indirectly; second, the configuration of the integrated winding is the same as one set of overlapping winding, which contains only one coil configuration and simplifies the manufacture process. In this article, the structure and operation principle of the integrated winding are detailedly introduced, and the electromagnetic performance of BLDD machine equipped with integrated winding is investigated by finite element analysis (FEA), finally a prototype is also manufactured and tested to verify the analysis.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Fatigue Mechanism of Die-Attach Joints in IGBTs Under Low-Amplitude
           Temperature Swings Based on 3D Electro-Thermal-Mechanical FE Simulations
    • Pages: 3033 - 3043
      Abstract: Fatigue failure of insulated gate bipolar transistor modules (IGBTs) packages under low-amplitude temperature swings is of great significance for the reliability evaluation of IGBTs operating in actual power electronic devices. In this article, failure mechanism of die-attach joints in IGBTs under normal operating and accelerated aging was comparably investigated by a three-dimensional electro-thermal-mechanical coupled model. Results indicated that local viscoplastic deformation of solder alloys around stress concentrated areas caused by material microdefects is the root cause of fatigue of die-attach joints under low-amplitude temperature swings. Fatigue cracks can only initiate and propagate at those plastically deformed areas (activation points). Fatigue of die-attach joints is co-determined by the number of activation points and crack growth rate. Comparably, the whole die-attach solder is in viscoplastic deformation under accelerated aging and the number of activation points has reached its saturation. Fatigue of die-attach joints under accelerated aging is only determined by the crack growth rate. Due to the difference in failure mechanism, it is questionable to directly extend conventional life models to normal operating conditions. Accordingly, an energy-based physical life model for die-attach joints in IGBTs under low-amplitude temperature swings was proposed.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Switching-Based Optimized Sliding-Mode Control for Capacitor Self-Voltage
           Balancing Operation of Seven-Level PUC Inverter
    • Pages: 3044 - 3057
      Abstract: Seven-level packed U-cell (PUC7) is known as a cost-effective low-component multilevel inverter. However, PUC7 challenge is the capacitor voltage balancing; so, it conventionally needs an additional voltage control integrated into the current control loop. Because of extra variables, the control problem is further complicated for the grid-connected PUC7. This article proposes an optimized sliding-mode control (OSMC) based on the current dynamical model to track the load current reference and to self-balance the capacitor voltage in both grid-connected and stand-alone operations. By optimizing the OSMC control factor using a visual-based optimization method, PUC7 switching operation is controlled to self-balance the capacitor voltage while any extra voltage controller is needed. An adaptive control law has been also proposed for self-tuning of the PUC7 current reference to track the load and dc source variations. Experimental and simulation results of PUC7 prove the excellent performance of the proposed OSMC in achieving capacitor self-voltage balancing operation.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Low-Frequency DC-Link Capacitor Current Mitigation in Reduced Switch Count
           Single-Phase to Three-Phase Converter
    • Pages: 3058 - 3068
      Abstract: This article proposes an approach to mitigate the dc-link double-frequency ripple current in a three-leg single-phase to three-phase converter. This article is based on an economical active phase converter (APC) utilizing a fewer number of switches. The presented approach does not demand either bulky dc side passive ripple filter or additional semiconductor switches typically employed in active dc-link ripple filters. The proposed method introduces an appropriately selected ac capacitor into the APC circuit, also known as auxiliary capacitor-based APC, which mitigates the dc-link double-frequency ripple. Reduction of power loss in the equivalent series resistor of the dc-bus capacitor associated with the dc-link double-frequency ripple current enhances the lifetime of electrolytic capacitor typically employed in the APC. At full load, the dc-link current at double-fundamental frequency is reduced by more than 50$%$ and the temperature rise in the dc-bus electrolytic capacitors is reduced by more than 30$%$. The proposed method is validated experimentally using a laboratory prototype APC. Theoretical and simulation results of the dc-link double-frequency current are in close agreement with the experimental findings.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • A Double-Side Self-Tuning LCC/S System Using a Variable Switched Capacitor
           Based on Parameter Recognition
    • Pages: 3069 - 3078
      Abstract: In order to allow a wireless power transfer system to operate in a large-scale space where coupling coefficient has a significant variation due to different air gaps and displacements, a double-side self-tuning LCC/S system using a variable switched capacitor based on parameter recognition is proposed in this article. The main innovation is that the parameter recognition method is able to recognize both mutual inductance and double-side self-inductance with only rms value of sampling signal, phase information and auxiliary circuit being needless. Besides, based on the result of parameter recognition, the double-side use of variable switched capacitors and corresponding control strategy allow the proposed system to operate in a large-scale coupling space and help to improve system efficiency. Experiment results show parameters recognizing error less than 5%. A contrastive simulation verifies that variable switched capacitor can be equivalent to discrete capacitor with the same branch current in the proposed system. System feasibility is testified by a 700-W prototype and the effectiveness of the proposed system is demonstrated by a contrastive experiment with and without pulsewidth modulation (PWM) tuning, efficiency from dc to dc will increase about 3% with PWM tuning.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Stability Analysis of Voltage Controlled Buck Converter Feed From a
           Periodic Input
    • Pages: 3079 - 3089
      Abstract: The ripples of dc input voltage belong to cascaded systems are usually close to the sinusoidal voltage, and its stability is quite different from that of dc constant voltage converters. Under the premise of no loss of generality, this article takes the output voltage of front-end converter in a cascaded system as sine wave, discusses the principle of closed-loop switching converters driven by sinusoidal input voltage, and calculates the average value of fixed-point state variables by using a discrete-time mathematical model. In addition, Filippov method is adopted to predict bifurcation by calculating the eigenvalues of Monodromy matrix belonging to the whole system, and the mechanism of nonlinear phenomena is also addressed. The results show that bifurcation points change obviously under different input conditions. Moreover, the influence of sinusoidal ripples amplitude and phase shift on bifurcation behavior is discussed, the compensation technique is used to prevent bifurcation and obtain the extended stability region of the circuit parameters. The experimental results prove the validity of the analysis.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Noniterative Design of Litz-Wire High-Frequency Gapped-Transformer
           (Lw-HFGT) for LLC Converters Based on Optimal Core-Geometry Factor Model
           (OKGM)
    • Pages: 3090 - 3102
      Abstract: Litz-wire high-frequency gapped-transformer (Lw-HFGT) is a vital component that facilitates efficient operation of LLC converters. The converter designers go through cumbersome multiobjective optimization techniques, with many iterations, to obtain an optimal Lw-HFGT design. High reliance on such techniques is due to deficiencies in existing analytical core and winding selection (CWS) methodologies; most analytical CWS models do not focus on optimization. Therefore, this article proposes noniterative analytical CWS methodology for Lw-HFGT based on an innovative optimal core-geometry factor model (OKGM). The aim is to obtain Lw-HFGT design with minimized losses and size, integrated magnetizing inductance, and temperature rise within limits. The method incorporates application requirements (excitation-voltage waveform, LLC circuit-parameters, thermal limit), along with Lw-HFGT physical characteristics [core geometrical features, peak flux density $(B_{{rm{pk}}})$, current density, core-material parameters, air-gap, effective permeability, and Litz-wire-sizing (LwS)] in the CWS process. Analytical models with improved accuracy for core geometrical features extraction from core-geometry factor, optimal-$B_{{rm{pk}}}$, and LwS are also proposed. The complete methodology is improved based on proposed models, optimality criteria, application requirements, and energy storage inside gapped transformer. Optimal values of initial setup parameters, calculated using optimal-$B_{{rm{pk}}}$, enable OKGM to carryout optimal CWS in single iteration. The methodology is experimentally validated by designing Lw-HFGT for the 110-kHz, 200-W, 400–12 VDC LLC converter. The PC40-material-based Lw-HFGT design achieves up to 67% r-duction in volume-loss product, in comparison to various existing methods with the same input.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • A Single-Stage Low-Power AC–DC RGB-LED Driver With Switching
           Capacitor Control Scheme
    • Pages: 3103 - 3112
      Abstract: This article presents a single-stage ac–dc light-emitting diode (LED) driver to achieve current regulation of red, green, and blue (RGB)-LED strings and ac–dc rectification with high power factor. The advantages of single-stage topology include single inductor, lower component counts, and smaller form factor. To adaptively and accurately regulate RGB-LED strings a switching capacitor control scheme is adopted with the properties of dynamic voltage difference detection and fast bus voltage hopping. The dynamic voltage difference detection precisely detects the voltage difference between the R- and GB-LED strings while the fast bus voltage hopping can immediately adjust the bus voltage level. The experimental results are shown to verify the theoretical analysis of the proposed LED driver, and the transient response time is less than 0.3 μs, which is at least three orders faster than the previous work. The peak efficiency of the proposed LED driver is up to 88.6%.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • A Multiport Converter Interfacing Solar Photovoltaic Modules and Energy
           Storage With DC Microgrid
    • Pages: 3113 - 3123
      Abstract: In this article, a novel multiport converter (MPC) to interface different solar photovoltaic modules (SPM), and the battery with a 380 V dc microgrid is proposed. It is ensured that all the photovoltaic modules are operated at their respective maximum power points (MPPs), which is a unique feature of the proposed scheme. The boosting of the low voltages of the SPMs and that of the battery to 380 V is accomplished by involving a dc–dc converter along with a high-frequency transformer. The battery banks are charged directly from the power of the SPM without involving the high-frequency transformer. This significantly reduces the power flow path within the system. The MPC can operate in stand-alone mode or in microgrid connected mode as and when required. In the microgrid-connected mode, it is capable of realizing the MPP tracking, and at the same time, it is able to control the charging current of the battery as per the requirement of its charge controller. When MPC is operated in stand-alone mode, the voltage across the local loads are regulated at 380 V. The proposed MPC is modeled using the first component approximation method to facilitate the design of the appropriate controllers. The effectiveness of the proposed scheme is established by performing detailed simulation studies. A hardware prototype of the MPC is fabricated. Detailed experimental studies are carried out utilizing the developed prototype to confirm the viability of the proposed scheme.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Short-Term Self-Scheduling of Virtual Energy Hub Plant Within Thermal
           Energy Market
    • Pages: 3124 - 3136
      Abstract: Multicarrier energy systems create new challenges as well as opportunities in future energy systems. One of these challenges is the interaction among multiple energy systems and energy hubs in different energy markets. By the advent of the local thermal energy market in many countries, energy hubs’ scheduling becomes more prominent. In this article, a new approach to energy hubs’ scheduling is offered, called virtual energy hub (VEH). The proposed concept of the energy hub, which is named as the VEH in this article, is referred to as an architecture based on the energy hub concept beside the proposed self-scheduling approach. The VEH is operated based on the different energy carriers and facilities as well as maximizes its revenue by participating in the various local energy markets. The proposed VEH optimizes its revenue from participating in the electrical and thermal energy markets and by examining both local markets. Participation of a player in the energy markets by using the integrated point of view can be reached to a higher benefit and optimal operation of the facilities in comparison with independent energy systems. In a competitive energy market, a VEH optimizes its self-scheduling problem in order to maximize its benefit considering uncertainties related to renewable resources. To handle the problem under uncertainty, a nonprobabilistic information gap method is implemented in this study. The proposed model enables the VEH to pursue two different strategies concerning uncertainties, namely risk-averse strategy and risk-seeker strategy. For effective participation of the renewable-based VEH plant in the local energy mar-et, a compressed air energy storage unit is used as a solution for the volatility of the wind power generation. Finally, the proposed model is applied to a test case, and the numerical results validate the proposed approach.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Robust Control Strategies for SyRG-PV and Wind-Based Islanded Microgrid
    • Pages: 3137 - 3147
      Abstract: The nonlinearity in the consumption does not maintain steady voltage or frequency; therefore, in this article, a circular limited cycle oscillator frequency locked loop with prefilter (CLO-FLL-WPF) based control for voltage source converter control is used to achieve voltage and frequency regulation in an islanded microgrid (MG). This control is implemented to compensate local load reactive power, harmonic currents, and load unbalance. Besides, the active power of local loads is shared among the multiple energy sources. The CLO-FLL-WPF control technique performance is validated experimentally and through simulations by comparing it with the existing control algorithm in a MG. This MG is a combination of the solar photovoltaic array, pico-hydro turbine-driven synchronous reluctance generator, permanent magnet brushless dc generator based wind energy conversion, and battery storage. In traditional battery control, a proportional-integral control approach is used, which can cause a stability problem. Thereby, in this article, the bidirectional dc–dc converter control method is used, which provides improved stability and makes the controller design straightforward. Test results validate the effectiveness of the control algorithm under different dynamic and steady-state conditions.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Control for Power Converter of Small-Scale Switched Reluctance Wind Power
           Generator
    • Pages: 3148 - 3158
      Abstract: With the rapid development of wind power generation technology worldwide, the influence of intermittent and fluctuating characteristics of wind power generation on the microgrid and load is attracting a lot of attention along with its increasing penetration. Aimed at solving the problem that only wind speed variation is considered in the generation plan of traditional small-scale wind power generation applications, this article presents a set of control schemes for the switched-reluctance-generator-based small-scale wind power generation system with the integrated energy storage system. Considering the possibility of off-grid operation of small-scale wind power generation systems in the areas where the grid is weak or even uncovered, the proposed control scheme increases the consideration of dynamic changes in load and energy storage unit. To improve the utilization efficiency of small-scale wind power generation, a step control scheme is proposed combining maximum power tracking control with power balance control. The two-stage inverter is established to generate ac 110V/60Hz outputs by voltage closed-loop control in boost circuit of front stage and proportional integral (PI) control in the inverter circuit of the second stage. Finally, the effectiveness of the proposed control schemes is verified experimentally.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Reversible Wideband Hybrid Model of Two-Winding Transformer Including the
           Core Nonlinearity and EMTP Implementation
    • Pages: 3159 - 3169
      Abstract: Accurate high-frequency modeling of transformers is crucial for the analysis and simulations of the fast electromagnetic transients of power systems and smart grids. However, most high-frequency models do not include the effects of core nonlinearity and may lead to inaccurate results. This article proposes an improved wideband model considering core nonlinearity for single-phase two-winding transformers and its implementation in the Electromagnetic Transients Program (EMTP). The hybrid model is developed by merging the wideband admittance module and the duality-derived π module using filters with compensation. The duality-derived π module is developed from the direct application of the principle of duality. The wideband admittance module is developed based on discrete state equations using the technology of the modified vector fitting method. All parameters of the hybrid model are easy to be obtained because they are determined using terminal tests instead of the detail information of the transformer. Simulations and experiments, including inrush current, lightning excitation, and ferroresonance tests, show that the proposed hybrid model can accurately simulate both the low- and high-frequency transients of a single-phase two-winding transformer with a maximum difference of 5%.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • A Data-Driven Approach With Uncertainty Quantification for Predicting
           Future Capacities and Remaining Useful Life of Lithium-ion Battery
    • Pages: 3170 - 3180
      Abstract: Predicting future capacities and remaining useful life (RUL) with uncertainty quantification is a key but challenging issue in the applications of battery health diagnosis and management. This article applies advanced machine-learning techniques to achieve effective future capacities and RUL prediction for lithium-ion (Li-ion) batteries with reliable uncertainty management. To be specific, after using the empirical mode decomposition (EMD) method, the original battery capacity data is decomposed into some intrinsic mode functions (IMFs) and a residual. Then, the long short-term memory (LSTM) submodel is applied to estimate the residual while the Gaussian process regression (GPR) submodel is utilized to fit the IMFs with the uncertainty level. Consequently, both the long-term dependence of capacity and uncertainty quantification caused by the capacity regenerations can be captured directly and simultaneously. Experimental aging data from different batteries are deployed to evaluate the performance of proposed LSTM+GPR model in comparison with the solo GPR, solo LSTM, GPR+EMD, and LSTM+EMD models. Illustrative results demonstrate the combined LSTM+GPR model outperforms other counterparts and is capable of achieving accurate results for both 1-step and multistep ahead capacity predictions. Even predicting the RUL at the early battery cycle stage, the proposed data-driven approach still presents good adaptability and reliable uncertainty quantification for battery health diagnosis.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Linear Feedback Dead-Beat Control for Modular Multilevel Converters:
           Validation Under Faults Grid Operation Mode
    • Pages: 3181 - 3191
      Abstract: The cascaded control approach is widely used to control the modular multilevel converter (MMC). Such approach allows to manage all MMC state variables in a decoupling manner based on modes separation. This separation introduces conditions related to control objectives response time resulting in slow dynamics. This will limit the use of the potential of MMC energy that is considered as a freedom for ac and dc grids ancillary services. On another side, robustness properties for a given control are also of a great interest when considering unmodeled uncertainties and disturbances. Starting from these requirements, a linear feedback dead-beat control is proposed in this article to accelerate the inner loops and consequently the outer ones (control objectives). The proposed control, based on exact discrete-time model of the MMC in which the sampling period is considered a priory in the control design, is synthetized by taking into account the control outputs saturation. The stability proof of the control and the robustness analysis as well as experimental results under fault grid operations highlighted on small-scale MMC will be presented in this article. The comparison with a continuous-time sliding mode control shows the advantage of the proposed control regarding the response time and undesired oscillation reduction.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Batteryless Tire Pressure Real-Time Monitoring System Driven by an
           Ultralow Frequency Piezoelectric Rotational Energy Harvester
    • Pages: 3192 - 3201
      Abstract: Tire pressure monitoring system (TPMS) has been brought into the stringent regulatory frameworks of many countries in the automotive market. However, common commercial TPMSs must rely on a life-limited battery, which brings about some safety risks and environmental problems. It is worthy to note that energy harvesting approaches are promising to realize a batteryless TPMS. In this article, a rotation-driven piezoelectric energy harvester with eight typical nonlinear buckled bridges is proposed to effectively scavenge ultralow frequency kinetic energy. Thinned bulk PZT film is employed as the piezoelectric functional layer based on its excellent electromechanical factor. Gear-induced interwell oscillation mechanism ensures the effective deformation of the piezoelectric buckled bridges. The developed harvester can generate the effective output power of 8.9 mW under the optimal resistance of 3 kΩ at 8.3 Hz rotational frequency. The 47, 100, and 330 μF capacitors can be saturated at 14.5, 15.1, and 14.5 V during 10, 19, and 51 s, respectively. Additionally, a commercial TPMS can be effectively powered by this harvester when it works at more than a critical frequency locating at 3.0–3.7 Hz. The commercial TPMS can be operated in realtime when the applied rotational frequency is more than 8.3 Hz.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Effect of Communication Delay on Consensus-Based Secondary Controllers in
           DC Microgrid
    • Pages: 3202 - 3212
      Abstract: In a dc microgrid, proportional current sharing among the sources is recommended while maintaining the system voltage within the limits. To achieve this, secondary control is often employed along with the primary droop controllers. As secondary controllers rely on communicated values, a larger delay in the communication channel can make the microgrid system unstable. Some specific studies on stability issues related to communication delay are reported in the literature using simulation studies, polynomial approximation of delay term, or by tracing the eigenvalues. However, these methods are either impractical or will give erroneous results. Considering increasing deployment of dc microgrids globally using different communication technologies and associated delays, a generic analysis is required in this area. In this article, existing secondary controllers are categorized into four classes. A comparison of these four classes based on the maximum delay before becoming unstable, termed as delay margin, is performed. Further, an expression for sensitivity of delay margin to system parameters at steady-state operation is derived. This analysis would help in determining the suitability of different system parameters for dc microgrid applications. The analytically obtained delay margin values are verified with the help of simulation studies as well as experiments.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Nonlinear Model Predictive Control for the Energy Management of Fuel Cell
           Hybrid Electric Vehicles in Real Time
    • Pages: 3213 - 3223
      Abstract: This article proposes an energy management system (EMS) for a fuel cell (FC) hybrid electric vehicle. The EMS is based on nonlinear model predictive control (NMPC) and employs a recurrent neural network (RNN) for modeling a proton exchange membrane FC. The NMPC makes possible the formulation of control objectives not allowed by a linear model predictive control (MPC), such as maximum efficiency point tracking of the FC, while the RNN can accurately predict the FC nonlinear dynamics. The EMS was implemented on a low-cost development board, and the experiments were performed in real time on a hardware-in-the-loop test bench equipped with a real 3-kW FC stack. The experimental results demonstrate that the NMPC EMS is able to meet the vehicle's energy demand, as well as to operate the FC in its most efficient region. Moreover, a comparative study is performed between the proposed NMPC, a linear MPC, and hysteresis band control. The results of this comparative study demonstrate that the NMPC provides a better fuel economy and can reduce FC degradation.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Impedance Analysis and Stabilization of Point-to-Point HVDC Systems Based
           on a Hybrid AC–DC Impedance Model
    • Pages: 3224 - 3238
      Abstract: Stability analysis of the point-to-point high-voltage dc (HVdc) transmission systems is crucial for planning and operational purposes. However, due to the protection of trade secret and user privacy, it is difficult to have access to detailed information of the converters of an HVdc system. To avoid detailed information of the converters during system stability assessment, this article adopts a hybrid ac–dc impedance model along with a new network partitioning method to assess stability of the point-to-point HVdc system. The proposed method has the following advantages. First, in contrast to the conventional stability analysis methods, the number of right half-plane poles of the system minor-loop gain is not required. Second, different from the conventional impedance models, the hybrid ac–dc impedance excludes the impacts of the impedances of the ac grid and dc networks, to which the converter is connected. Accordingly, the hybrid ac–dc impedance model solely depends on the converter itself. In addition to the proposed method, this article demonstrates that the power flow direction of a point-to-point HVdc system has no impact on selection of different system minor-loop gains. Accuracy and effectiveness of the proposed method are evaluated and validated by time-domain and frequency-domain simulations in the MATLAB/Simulink environment.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Decoupling Control for DC Electric Spring-Based Unbalanced Voltage
           Suppression in a Bipolar DC Distribution System
    • Pages: 3239 - 3250
      Abstract: The use of bipolar direct current (dc) distribution systems introduces the possibility of unbalanced voltage (current). This situation increases the voltage deviations and power losses at each node owing to the presence of a neutral line current. This article proposes a method that mitigates the unbalanced voltage caused by constant power loads (CPLs) by dc electric springs (DC–ESs). A linearized model is used in the small-signal analysis of CPLs. On this basis, the coupling relationship between positive and negative pole voltages is analyzed. After DC–ESs are introduced, the positive and negative pole voltages and DC–ES output voltages are found to be closely related, thereby increasing the complexity of the control system. Therefore, a feedforward decoupling control block diagram is introduced on the basis of the small-signal model analysis of DC–ESs in a single node of the bipolar dc system. The control system is simplified, and different control loops can be independently controlled. Thus, the rapidity and anti-interference performance of the control system are greatly enhanced. Simulation and experimental results of the unbalanced voltage suppression in the bipolar dc system are used to verify the effectiveness of the proposed scheme.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Deep Neural Learning Based Distributed Predictive Control for Offshore
           Wind Farm Using High-Fidelity LES Data
    • Pages: 3251 - 3261
      Abstract: This article explores the deep neural learning (DNL) based predictive control approach for offshore wind farm using high-fidelity large eddy simulations (LES) data. The DNL architecture is defined by combining the long short-term memory (LSTM) units with convolutional neural networks (CNN) for feature extraction and prediction of the offshore wind farm. This hybrid CNN-LSTM model is developed based on the dynamic models of the wind farm and wind turbines as well as higher fidelity LES data. Then, distributed and decentralized model predictive control (MPC) methods are developed based on the hybrid model for maximizing the wind farm power generation and minimizing the usage of the control commands. Extensive simulations based on a two-turbine and a nine-turbine wind farm cases demonstrate the high prediction accuracy (97% or more) of the trained CNN-LSTM models. They also show that the distributed MPC can achieve up to 38% increase in power generation at farm scale than the decentralized MPC. The computational time of the distributed MPC is around 0.7 s at each time step, which is sufficiently fast as a real-time control solution to wind farm operations.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Circuit Modeling of the Mechanical-Motion Rectifier for Electrical
           Simulation of Ocean Wave Power Takeoff
    • Pages: 3262 - 3272
      Abstract: As is the case with several other mechanical power takeoffs (PTOs), the mechanical-motion-rectifier-based PTO consists of components, such as one-way clutches, gears, a ball screw, mechanical couplings, and a generator. Equivalent circuit models have been created in this article to describe the dry frictions, viscous damping, and mechanical compliances in these components, so the nonideal efficiency and nonlinear force of the PTO can be predicted in electrical simulations by integrating these subcircuit models. The circuit model is simplified, and its parameters are categorized as dc and ac unknowns. The dc and ac tests on the PTO are performed sequentially to extract two sets of parameters through linear regression or nonlinear curve fitting. Then, the model is validated through its prediction capability over 25 test conditions on input forces, output voltages, and efficiencies, with correlation coefficients of 0.9, 0.98, and 0.981, respectively.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • A Wireless Rectifier for Inductively Energizing High Direct-Current
           High-Temperature Superconducting Magnets
    • Pages: 3273 - 3281
      Abstract: High-temperature superconducting (HTS) magnets have been widely used in various applications due to their excellent performance. One long-lasting problem, however, is that they have to be powered by electronic power supplies via a pair of thick current leads, which go through room temperature environment into a cryogenic environment. The considerable heat load generated by these resistive current leads at a cryogenic temperature substantially limits the operating current and the energy density of the magnet. In this article, we report a novel mechanism of inductively energizing closed-loop HTS dc magnets. This exploits a newly discovered effect, which appears within a superconducting loop when a global screening current interacts with local screening current. This results in a dc voltage across the superconductor, which enables an alternating superconducting current to be rectified in order to energize a superconducting magnet. Based on this principle, a superconducting transformer–rectifier prototype is realized and demonstrated. Test results show that the prototype can output a dc voltage of up to 25 mV and a maximum direct current over 500 A. It is envisaged that this work will enable future HTS dc magnets to be operated in a closed cryogenic environment, eliminating the need for electronic power supplies and bulky current leads. This would greatly reduce the footprint and power demand of HTS magnet systems and unlock many new opportunities for the applications of this technology.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Simulation Credibility Assessment Methodology With FPGA-based
           Hardware-in-the-Loop Platform
    • Pages: 3282 - 3291
      Abstract: Electronic control systems are becoming more and more complicated, which makes it difficult to test them sufficiently only through experiments. Simulation is an efficient way in the development and testing of complex electronic systems, but the simulation results are always doubted by people due to the lack of credible simulation platforms and assessment methods. This article proposes a credible simulation platform based on real-time field programmable gate array (FPGA)-based hardware-in-the-loop (HIL) simulation, and then an assessment method is proposed to quantitatively assess its simulation credibility. By using the FPGA to simulate all sensor chips, the simulation platform can ensure that the tested electronic system maintains the same hardware and software operating environment in both simulations and experiments, which makes it possible to perform the same tests in the simulation platform and the real experiment to compare and analyze the simulation errors. Then, the testing methods and assessment indices are proposed to assess the simulation platform from various perspectives, such as performance, time-domain response, and frequency-domain response. These indices are all normalized to the same scale (from 0 to 1) and mapped to a uniform assessment criterion, which makes it convenient to compare and synthesize different assessment indices. Finally, an overall assessment index is proposed by combining all assessment indices obtained from different tests to assess the simulation credibility of the whole simulation platform. The simulation platform and the proposed assessment method are applied to a multicopter system, where the effectiveness and practicability are verified by simulations and experiments.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • An Efficient RRT-Based Framework for Planning Short and Smooth Wheeled
           Robot Motion Under Kinodynamic Constraints
    • Pages: 3292 - 3302
      Abstract: This article presents a framework that extends a rapidly exploring random tree (RRT) algorithm to plan the motion for a wheeled robot under kinodynamic constraints. Unlike previous RRT-based path planning algorithms that apply complex steer functions during a path sampling phase, this framework uses a straight line to connect a pair of sampled waypoints such that an obstacle-free path can be quickly found. This path is further pruned by the short-cutting algorithm. Under the kinodynamic constraints, we propose a motion-control law that is guided by a pose-based steer function for the robot to reach its destination in a short time. A path deformation strategy is presented that shifts the waypoint away from the collision point such that the trajectory can be generated without any collision. Simulation results demonstrate that the proposed framework needs less computation to generate a smoother trajectory with shorter length than its peers, and experimental results show that simulated trajectories of our controller are very close to real ones and the performance is better than that of a prior pose-based controller.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • CoboSkin: Soft Robot Skin With Variable Stiffness for Safer
           Human–Robot Collaboration
    • Pages: 3303 - 3314
      Abstract: Conventional industrial robots are unable to guarantee the inherent safety when working together with humans due to the use of rigid components and the lack of force sensation. To enhance the safety of human–robot collaboration (HRC), the new collaborative robot skin (CoboSkin) with the features of softness, variable stiffness, and sensitivity is designed and studied in this article. The CoboSkin is composed of an array of inflatable units and sensing units. The sensing units made of soft porous materials are capable of measuring distributed contact force in a real-time manner. By leveraging the foaming process, the sensing units are interconnected with inflatable units fabricated by the elastomer of which the deformation is limited by the textile wrapped around it. Variation of stiffness is enabled by adjusting the internal air pressure supplied to inflatable units, thereby changing the sensitivity of the sensing units and reducing the peak impact force. Soft porous materials endowed the CoboSkin with increased sensitivity, minimal hysteresis, excellent cycling stability, and response time in the millisecond range, which enabled sensing feedback for controlling a robot arm at different levels of stiffness. Finally, the validation of the CoboSkin for safer HRC was conducted with a robot arm to detect an unintended collision, illustrating its potential application in robotics.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Linear Modeling and Control of Comb-Actuated Resonant MEMS Mirror With
           Nonlinear Dynamics
    • Pages: 3315 - 3323
      Abstract: This article presents a novel method to derive and identify an accurate small perturbation model of a comb-actuated resonant microelectromechanical system (MEMS) mirror with highly nonlinear dynamics. Besides the nonlinear stiffness and damping, the comb-drives add nonlinearities due to their electrostatic nature and their effect on the dynamic mirror amplitude over frequency behavior. The proposed model is based on a period to period energy conservation and applies for most nonlinearities present in an oscillator such as MEMS mirrors. It is shown that for specific nominal operation points with square wave excitation, the small perturbation model is linear for a wide range. The full dynamics of the derived linear model are parametrized by three constants, that can be estimated by the phase locked loop (PLL), performing a proposed identification method only based on phase measurements. An analysis of control laws usually applied in a PLL provides important information for the proper design of controllers to meet the desired behavior for individual applications.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Pose Sensing and Servo Control of the Compliant Nanopositioners Based on
           Microscopic Vision
    • Pages: 3324 - 3335
      Abstract: This article presents new pose sensing and servo control techniques for the compliant nanopositioners (CNPs) based on optical microscopic vision. A visual pose tracking algorithm (VPTA) and a visual servo positioning scheme (VSPS) that both utilize iterative template matching are presented. In the VPTA, to realize pose sensing of the CNPs with high performance, an improved Gaussian–Newton optimization method combined with an adaptive penalty strategy is developed. In the VSPS, to realize robust and flexible control of the CNPs, a velocity controller that directly uses the gray value of the template to control the CNP is designed. Simulations and experiments are performed to demonstrate the performance of the proposed method. Results show that the VPTA can achieve pose tracking of the three-degree-of-freedom ($x$, $y$, $theta$) CNPs at a frame rate of hundred hertz, and the dynamic tracking errors are smaller than 100 nm, 160 nm, and 40 $mu {text{rad}}$ in the $x$-, $y$-, and $theta$-axes, respectively. Moreover, by using the proposed VSPS, task-based nanopositioning can be easily realized without extracting features of the object, and the obtained stable positioning accuracies are better than 30 nm, 33 nm, and 3 $mu {text{rad}}$ in the $x$-, $y$-, and $theta$-axes, respectively.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Research on Selection Criterion of Design Tolerance for Air-Core Permanent
           Magnet Synchronous Linear Motor
    • Pages: 3336 - 3347
      Abstract: In the design and manufacturing process of permanent magnet synchronous linear motors (PMSLMs), tolerance select will directly influence the thrust performance of the motor. This article investigates the selection criterion of design tolerance for the PMSLMs, which are applied in the laser cutting machine, and select an appropriate tolerance range that meet the thrust performance and at low manufacturing cost. First, analytical analysis is used to determine the relationship between the geometric tolerance of the air gap and the thrust performance and finite element analysis is used to confirm the analytical results. Then, the extreme learning machine is introduced to thrust modeling with high-precision and high-efficiency. Furthermore, the geometric tolerance range of the air-gap is solved under the requirement of the PMSLM through genetic algorithm and allocated to the relevant parts. Finally, the effectiveness of tolerance selection is validated through the PMSLM prototype experiment.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Modeling and Control of Piezoelectric Hysteresis: A Polynomial-Based
           Fractional Order Disturbance Compensation Approach
    • Pages: 3348 - 3358
      Abstract: Piezoelectric hysteresis is a critical issue that significantly degrades the motion accuracy of piezo-actuated nanopositioners. Such an issue is difficult to be precisely modeled and compensated for, primarily due to its asymmetric, rate, and input amplitude-dependent characteristics. This article proposes a novel method to deal with this challenge. Specifically, a polynomial-based fractional order disturbance model is proposed to accommodate and characterize the complex hysteresis effect. In this model, the rate dependence is captured by a general method of implementing curve fitting in Bode magnitude plot. The inverse model for control purposes is immediately available from the original one. The proposed method does not require expensive computational resources. In fact, this article shows that this controller can be easily implemented in an analog manner, which brings the advantages of high bandwidth and low cost. Extensive modeling and tracking experiments are carried out to demonstrate the effectiveness of the proposed method. It is shown that the piezoelectric hysteresis nonlinearity can be significantly suppressed over a wide bandwidth.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • On Convergence Performance of Discrete-Time Optimal Control Based Tracking
           Differentiator
    • Pages: 3359 - 3369
      Abstract: Time optimal control (TOC) based tracking differentiator (TD) was first proposed by Han as a practical solution to avoid setpoint jump in active disturbance rejection control. In practice, the discrete-time optimal control (DTOC) is implemented in the form of state feedback for a double-integral system, which is widely used to design controllers, observers and noise-tolerant differentiators. The convergence of the DTOC-TD, however, has not been fully understood. This article provides a rigorous full convergence analysis of the DTOC-TD. It then illustrates the frequency-domain characteristics of this DTOC-TD in signal-tracking filtering and differentiation acquisition, giving a rule of thumb for regulating the parameters. Finally, the case studies including comparison simulations and experiments on processing gap sensor’ signals in the suspension system of maglev train are carried out to verify the effectiveness of the DTOC-TD.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Field-Programmable System-on-Chip-Based Control System for Real-Time
           Distortion Correction in Optical Imaging
    • Pages: 3370 - 3379
      Abstract: The digital transition requires real-time control of complex systems with short loop time and low latency in various applications. Field-programmable gate arrays (FPGAs) are, in principle, capable of complying with this task but demand, on the other hand, a high programming effort. In this article, we propose a field-programmable system on chip (FPSoC) as a hybrid solution of an FPGA and a central processing unit (CPU) on a single monolithic die to combine the strengths of both architectures. An FPSoC-based adaptive optical wavefront correction system is presented as a case study to correct camera images in real time that are distorted by time-varying aberrations. While a short total loop time is achieved by interfacing the camera and a deformable mirror on a low level directly with the FPGA, all computationally nonintensive tasks are implemented on the CPU to keep the flexibility, reusability, and development expense low. The system corrects the optical distortion of water surface waves with up to 3600 control cycles per second and spatially attenuates the distortion up to Zernike polynomial 14 with up to 150 Hz. The FPSoC system enables fast spatiotemporal aberration correction in technical processes and offers a perspective for measuring complex flows through fluctuating interfaces.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Robust Model-Predictive Control for Inductively Coupled Plasma Generation
           With a Semiphysical Simulation
    • Pages: 3380 - 3389
      Abstract: In this article, a novel robust tuning approach based on model-predictive control (MPC) for an inductively coupled plasma (ICP) generation process is presented. Several key aspects related to this methodology are the modeling of the ICP generation process, the robust joint tuning (RJT) algorithm, and the semiphysical simulation of the MPC algorithm. The ICP generation process model is built by a system identification method based on steady and dynamic responses, followed by a general model-predictive controller. Then, an automatic RJT algorithm is developed for the model-predictive controller to quickly obtain the optimal weighting parameters. The proposed RJT algorithm can minimize the ICP generation control system's maximum total variations in the output with a specific dynamic performance requirement and model uncertainty, providing a tradeoff between the dynamic performance and robustness. Finally, a semiphysical simulation system based on dSPACE and a field-programmable gate array is designed to illustrate the effectiveness of the model-predictive controller for the ICP generation control process and the RJT algorithm. Experimental results indicate the validity and good performance of the proposed model-predictive controller and the RJT algorithm.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Robust Multilayer Model Predictive Control for a Cascaded Full-Bridge NPC
           Class-D Amplifier With Low Complexity
    • Pages: 3390 - 3401
      Abstract: Model predictive control (MPC) has the advantages of good dynamic performance and the ability to handle multiple control objectives and constraints. However, it suffers from large amount of calculation and high dependence on system model when it is applied to cascaded inverters. In this article, to solve this problem, a robust multilayer MPC (RM-MPC) with strong robustness and less computation is proposed for Class-D amplifier using cascaded full-bridge NPC inverter. A Kalman filter-based disturbance observer is designed to estimate the lumped disturbance caused by the mismatches of the load parameters, which allows to implement robust control by compensating the disturbance to the predictive model during each control period. In the upper layer of the multilayer MPC, the control objectives that are linear with the output level are handled centrally, which allows the optimal level to be obtained directly without repetitive predictions and evaluations. The middle layer is used to allocate the optimal level to each submodule. And the lower layer is used to determine the switching state of each submodule. Finally, the feasibility and validity of the RM-MPC are verified on the designed experimental prototype.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Event-Triggered Dynamic Surface Control of an Underactuated Autonomous
           Surface Vehicle for Target Enclosing
    • Pages: 3402 - 3412
      Abstract: This article addresses the event-triggered dynamic surface control of an underactuated autonomous surface vehicle with unknown kinetics for circumnavigating a dynamic target with unknown velocity. A modular design approach to the event-triggered dynamic surface control is proposed for target enclosing. In the estimator module, an extended state observer is employed for estimating the relative motion between the target and the surface vehicle. A fuzzy system is used for online modeling the unknown vehicle kinetics. In the controller module, an event-triggered dynamic surface control law is constructed by using the estimated relative velocities and vehicle kinetics in the estimator module. In the control law, a triggered mechanism is introduced to reduce the transmission load and the execution rate of actuators. Besides, the control inputs are bounded with the aid of a projection operator and saturated functions. The input-to-state stability of the closed-loop target enclosing system is proven through Lyapunov analysis. Simulation results substantiate the effectiveness of the event-triggered dynamic surface control method for circumnavigating a maneuvering target.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Robust Indoor Speaker Localization in the Circular Harmonic Domain
    • Pages: 3413 - 3422
      Abstract: In this article, modal signal processing using circular sensor arrays has been shown to be an attractive way for speaker localization, due to the fact that it enables high flexibility in sound field analysis, which inherently supports wideband acoustic sources and provides a frequency invariant beampattern. However, the existing circular harmonic direction-of-arrival (DOA) estimation approaches suffer from the following problems: first, depending strongly on the characteristics of sensor arrays; second, the presence of singularity when using Bessel function of the first kind; and third, being sensitive to noisy and reverberant environments. To combat these problems, this article proposes a robust indoor speaker localization method that incorporates circular harmonic pseudointensity vector through joining the least-squares decomposition and the spatial processing with a small-sized sensor array. The root mean square error of DOA estimation of the proposed method is compared with those published approaches in simulations for different noise levels and reverberation times. In addition, the superior performance of the proposed indoor speaker localization method is validated by using speech recordings in a real-world acoustic environment.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Analytical Solution for Nonlinear Three-Dimensional Guidance With Impact
           Angle and Field-of-View Constraints
    • Pages: 3423 - 3433
      Abstract: An analytical 3-D guidance law with impact angle and field-of-view (FOV) constraints considering nonlinear coupled dynamics is proposed. As a stepping stone, the guidance model is transformed to a set of nonlinear differential equations in terms of the relative range variable. To meet the desired impact angles in the pitch and yaw planes, two cubic polynomials including eight coefficients are developed with respect to the relative range for creating reference line-of-sight (LOS) profiles. The unknown coefficients are explicitly solved by initial and terminal conditions on the LOS angles and LOS rates in the mutually orthogonal planes. Then, the analytical 3-D impact angle guidance (IAG) law is derived via formulating the second-order LOS dynamics of the transformed model. Moreover, the relation between the seeker's look angle and the reference LOS profiles is developed, such that the achievable impact angle set can be obtained to handle the FOV limit. Numerical simulations with comparison study and a realistic model are conducted to verify effectiveness and robustness of the guidance law. Its feasibility is additionally validated by applying it to the guidance of unmanned aerial vehicles landing on surface moving carriers.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Velocity Control for Sideband Harmonics Compensation in Permanent Magnet
           Synchronous Motors With Low Switching Frequency Inverter
    • Pages: 3434 - 3444
      Abstract: The existing methods for improving the control performance of permanent magnet synchronous motors (PMSMs) do not consider the effect of sideband harmonics during the intrinsic switching process in inverters. Undesirable sideband harmonics increase when the switching frequency of inverters is not sufficiently high compared to the fundamental frequency. These large sideband harmonics lead to torsional oscillations, which may severely damage motion control systems. In this article, we propose velocity control to reduce sideband harmonics in PMSMs with a low switching frequency inverter. The proposed method consists of a velocity controller and a sideband harmonics compensator. The desired dynamics for velocity tracking are developed via a PMSM model. The velocity controller is developed to improve velocity control performance using the desired dynamics. The sideband harmonics compensator is designed by utilizing sideband harmonics dynamics, which are proposed to suppress the main components of the sideband harmonics. First, a sideband harmonics observer is developed to estimate the sideband harmonics using sideband harmonics dynamics. Then, the sideband harmonics are rejected by the sideband harmonics compensator. The stability of the closed loop is proven by employing the input-to-state stable property. The performance of the proposed method is validated via experiments.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Attention Recurrent Neural Network-Based Severity Estimation Method for
           Interturn Short-Circuit Fault in Permanent Magnet Synchronous Machines
    • Pages: 3445 - 3453
      Abstract: With the development of smart factories, deep learning, which automatically extracts features and diagnoses faults, has become an important approach for fault diagnosis. In this article, a novel interturn short-circuit fault (ISCF) diagnosis approach using an attention-based recurrent neural network is proposed. An encoder–decoder architecture using an attention mechanism diagnoses the ISCF by estimating a fault indicator that directly reflects the severity of the fault, using currents and rotational speed signals as inputs. The attention mechanism helps the decoding process in accurate diagnosis and solves the long-term dependence problem of the encoder–decoder structure. The proposed algorithm uses only three-phase current and rotational speed as the inputs to evaluate the severity of the ISCF and enable early stage diagnosis of ISCF. The diagnosis of ISCF is achieved in various operating points and fault conditions, and no additional sensors, such as voltage and vibration sensors, are required. Experimental results for various operating and fault conditions demonstrate that the proposed method effectively diagnoses ISCFs.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Domain Knowledge-Based Deep-Broad Learning Framework for Fault Diagnosis
    • Pages: 3454 - 3464
      Abstract: Intelligent fault diagnosis is a vital role in smart manufacturing. And deep-learning-based fault diagnosis has become a hot topic due to its strong feature extraction ability. However, traditional deep-learning-based methods show two limitations. One is that a large number of labeled samples are required to construct effective diagnosis models. Another is that these methods lack flexibility, especially for homologous multitasking problems. In this article, a novel domain-knowledge-based deep-broad learning framework (DK-DBLF) is proposed to overcome abovementioned limitations. A DK-DBLF consists of two parts: a task-specific feature extractor and a flexible fault recognizer. The first part is constructed by several convolutional neural networks to obtain abstract features automatically, and the second part employs a broad learning system to improve the flexibility of the proposed framework. To combine these two parts more effectively, bridge label-based strategy is designed, which is a key connection that can integrate domain knowledge into the learning process. The performance of a DK-DBLF is tested on motor-bearing and pipeline defect datasets, which are health condition classification and homologous multitask estimation problems, respectively. The results have demonstrated that our framework can significantly reduce the usage of labeled samples in the learning process, and architecture adjustment can be easily performed when compared with traditional deep methods.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Cluster-Based Vibration Analysis of Structures With GSP
    • Pages: 3465 - 3474
      Abstract: This article describes a divide-and-conquer strategy suited for vibration monitoring applications. Based on a low-cost embedded network of microelectromechanical accelerometers, the proposed architecture strives to reduce both power consumption and computational resources. Moreover, it eases the sensor deployment on large structures by exploiting a novel clustering scheme, which consists of unconventional and nonoverlapped sensing configurations. Signal processing techniques for inter- and intracluster data assembly are introduced to allow for a full-scale assessment of the structural integrity. More specifically, the capability of graph signal processing is adopted for the first time in vibration-based monitoring scenarios to capture the spatial relationship between acceleration data. The experimental validation, conducted on a steel beam perturbed with additive mass, reveals high accuracy in damage detection tasks. Deviations in spectral content and mode shape envelopes are correctly revealed regardless of environmental factors and operational uncertainties. Furthermore, an additional key advantage of the implemented architecture relies on its compliance with blind modal investigations, an approach that favors the implementation of autonomous smart monitoring systems.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Reliable Detection of Stator Interturn Faults of Very Low Severity Level
           in Induction Motors
    • Pages: 3475 - 3484
      Abstract: The interturn faults are one of the most (if not the most) challenging electrical machine failures to detect online and at incipient severity stages. Past works and experience have shown that this specific fault type will lead to a ground fault and consequently a catastrophic failure of the machine in a very small amount of time. Past works have proposed techniques and methodologies to confront this dangerous fault. However, a common feature in most past efforts is the high level of severity, limited by external resistors to avoid machine breakdowns. Scenarios like the above are not of much use in industry because they lead to the development of diagnostic techniques insensitive to the real fault severity levels that are noncatastrophic and that are by their nature very low. This is the motivation behind this article, which challenges the existing background in this field and offers a reliable solution, which may be adopted in industry. The article studies induction motors with incipient interturn fault severity with many well-known techniques. The experimental results prove many methods unreliable and insensitive to low level interturn fault detection. Finally, the authors propose a novel method that relies on the monitoring of the stray flux at three positions of the machine.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • A Novel Prognostics Approach Using Shifting Kernel Particle Filter of
           Li-Ion Batteries Under State Changes
    • Pages: 3485 - 3493
      Abstract: Lithium-ion (Li-ion) batteries are used in various applications as the rechargeable power sources. The batteries undergo capacity fade during the repeated charge–discharge cycles, which eventually leads to the end of life (EOL). For the purpose of timely replacement before reaching the EOL, reliable prediction of the remaining useful life (RUL) during the cycles is of great importance. However, there may exist unhealthy batteries exhibiting the change of state at some cycles from those of normal degradation, which leads to their EOL sooner than expected. In this article, we propose a novel prognostic method using the particle filter (PF) that is capable of detecting the point of state change and adapting its algorithm to the new battery degradation pattern. The performance of the proposed method is demonstrated by the case study of Li-ion battery degradation data, comparing with the original PF algorithm. As a result, the proposed method shows better performance in terms of anomaly detection of degradation and adaptability to the new degradation process, which leads to more accurate and reliable RUL prediction.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Lateral and Torsional Vibration Monitoring of Multistack Rotor Induction
           Motors
    • Pages: 3494 - 3505
      Abstract: In this article, both the lateral and torsional vibrations in multistack rotor induction motors (IM) are modeled in the same framework, and the corresponding precursors in the current waveform are analyzed in detail. Due to the very large rotor length-to-diameter ratio, rotor vibrations can become a major issue in these types of high-torque motors. In order to monitor the vibration components, the lumped mass–spring model for the rotors and couplings is developed to calculate the natural frequencies and torsional-mode shapes of the mechanical system. To model the electrical part, stator windings are split up into several identical windings that are connected in series and correspond to each rotor stack. Since the torsional vibration does not remarkably affect the winding symmetry, the dq model for each section is sufficient to describe the motor behavior during torsional oscillation. Similarly, for the lateral vibration, the mechanical system is modeled in all lateral directions and all modes. Due to the loss of symmetry, the abc model is used for each rotor and stator. In this modeling approach, all inductances (self and mutual of stator and rotor and the mutual inductances between the stator and rotor) are needed. To mimic the effect of lateral vibrations on the motor inductances, a new approach is developed using winding function theory. In this model, all inductances are formulated as a function of eccentricity severity and angle, and a new analytical IM model is developed to show the effects of lateral vibration. Finally, the experimental results are presented and compared with the analytical results.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • FFCNN: A Deep Neural Network for Surface Defect Detection of Magnetic Tile
    • Pages: 3506 - 3516
      Abstract: Surface quality assessment of magnetic tile before mounting is extremely significant. At present, this task is mainly accomplished by experienced workers in industry, which exposes the drawbacks of low efficiency and high cost. To overcome these issues, an intelligent system is developed to perform this task, which appears to be an efficient and reliable substitute for human workers. In this article, deep learning technique is embedded into our system for automatic defect identification. However, conventional convolutional neural network (CNN) is not suitable for this classification task, since the input is a sample rather than a single image. To overcome this problem, an end-to-end CNN architecture is proposed, termed fusion feature CNN (FFCNN). FFCNN consists of three modules: feature extraction module, feature fusion module, and decision-making module. The feature extraction module is designed to extract features from different images. The feature fusion module is to fuse the features extracted by feature extraction module. The decision-making module is to predict the label by the fused features. Furthermore, an attention mechanism is introduced to focus on more representative parts and suppress less important information. Experimental results demonstrated that the developed system is effective and efficient for magnetic tile surface defect detection.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Fixed-Frequency Low-Loss Dielectric Material Sensing Transmitter
    • Pages: 3517 - 3526
      Abstract: This article presents an all-in-one system for the detection of the relative permittivity of samples in direct contact with a sensor antenna, based on the frequency variation detection and using a cost- and energy-effective manner. In a specific application, in which the antenna should be in contact with the sensing material, characteristics of the antenna change with respect to the frequency spectrum for different materials. Conventionally, a frequency spectrum monitoring device is required to monitor these changes, and the sensing data should be obtained by postprocessing the observation. The proposed system converts the sensing information in the frequency response of the device to a voltage, which can be utilized further for transmission as well as compensating and frequency retuning the system. The sensor antenna loads the radio frequency oscillator at the transmitter resulting in a change at the operating frequency of the system. A small portion of the signal is sampled and used for recovery in a phase/frequency comparator (PFC). The output of the PFC is a voltage corresponding to the difference between the operating frequency and the reference signal. The proposed sensor system is fabricated at the 915-MHz ultrahigh-frequency radio frequency identification band using on–off keying modulation as an evaluation, and the measured results with some known samples are presented. Since the proposed technique is implemented by utilizing the building blocks of a conventional transmitter, the power consumption and cost of the system are kept intact.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • A Magnetoelectric Compass for In-Plane AC Magnetic Field Detection
    • Pages: 3527 - 3536
      Abstract: Magnetoelectric (ME) composites exhibit high sensitivity for detecting the strength of weak magnetic field. Yet, they are not sensitive to the angle of a randomly orientated in-plane ac magnetic field, since the strain-mediated ME structures merely response to magnetic field along certain direction. In this article, an ME compass for detecting the intensity as well as the orientation of in-plane ac magnetic field is proposed. The ME compass is designed with the barbell-shaped structure, where NdFeB permanent magnets induce compressive stress on piezoelectric components via torque effect, so that the magneto-mechano-electric coupling effect is mediated by stress without dc magnetic bias field. The ME compass reveals a low resonant frequency (
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Novel Multistate Fault Diagnosis and Location Method for Key Components of
           High-Speed Trains
    • Pages: 3537 - 3547
      Abstract: Images collected by linear scan cameras are stretched and compressed due to the speed regulation of trains. This condition changes the shape of objects and considerably increases the false and missed alarm rates. Moreover, small size and dense distribution of the key components in railway trains increase the difficulty in fault diagnosis. Therefore, a two-module troubleshooting and positioning methodology is proposed, in this article, for state diagnosis of key small components of high-speed running trains. First, the image with deformation is reshaped to be exactly the same as the standard one via omnidirectional scale correlation normalization (OSCN), which performs well even in low texture, high-light situations. Second, we propose three feature-enhanced models to expand the receptive field of deep feature maps. This novel detector, namely, refine-inception net (RIN), not only reduces the rate of missed and false detection, but also minimizes the influence of target size and occlusion. Augmentation is performed to increase robustness because the detector is data driven. Experimental results show that the optimal strategy combining OSCN and RIN can troubleshoot high-speed trains of different models with an accuracy higher than 99%. Our method can be extended to foreign object recognition on the train roof while maintaining railway safety.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Design and Realization of a Compact High-Precision Capacitive Absolute
           Angular Position Sensor Based on Time Grating
    • Pages: 3548 - 3557
      Abstract: This article proposes a compact and high precision capacitive absolute angular position sensor based on time grating. The sensor consists of a stator and a rotor with three concentric capacitor structures forming primary and auxiliary angular displacement measurement components. The primary component combines a single middle-row capacitive structure with an outer-row capacitive structure to obtain high-precision displacement measurements composed of N measurement periods. The auxiliary component employs a single inner-row capacitive structure with a single spatial period over the 360° measurement range of the sensor in conjunction with a remodulation scheme to obtain displacement measurements composed of N − 1 measurement periods. Combining the measurements of the primary and auxiliary components in a manner similar to vernier calipers yields high-precision absolute angular position measurements. The sensor design and remodulation scheme facilitate good sensor compactness. The measurement performance of the proposed design is evaluated via tests of a prototype sensor with an outer diameter of 60 mm fabricated by printed circuit board technology. The prototype sensor is demonstrated to obtain a measurement resolution of 3" and a measurement accuracy of ±10" over the 360° measurement range of the sensor, indicating that the proposed sensor design has considerable potential for high precision applications.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • A 65 nm CMOS Statistical Frequency Ratio Calculator for Frequency
           Measurement
    • Pages: 3558 - 3566
      Abstract: In this article, the frequency ratio calculator (FRC) based on the statistical algorithm is proposed to obtain the integer and fractional frequency ratios of an input signal and a reference signal. The function of FRC can be used for fast frequency measurement of an unknown signal. Thanks to the proposed statistical algorithm, the circuit implementation of the FRC can be realized by synthesis of CMOS standard cell library and its performance is resistant to the variation of process, voltage, and temperature. The FRC is developed in a commercial 65 nm CMOS technology and its input signal frequency range is from 300 MHz to 1.5 GHz. The ratio calculation time takes only two reference cycles and the ratio accuracy is better than 0.003. The FRC consumes 12–42 mW of power from a 1.2 V supply voltage for different input frequency.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • An SoC-FPGA-Based Iterative-Closest-Point Accelerator Enabling Faster
           Picking Robots
    • Pages: 3567 - 3576
      Abstract: The conventional picking robots suffered from low picking throughput due to a large amount of computation of the object-pose-estimation algorithm which is called iterative-closest-point (ICP) algorithm. This article presents an field-programmable gate array (FPGA)-based ICP accelerator, which achieves 11.7-times-faster object-pose estimation by a picking robot compared with the state-of-the-art technique based on K-D-tree k-nearest neighbor (NN) search and four-core CPU. To accelerate the ICP, both algorithm-level and hardware-level techniques have been proposed and developed. The former is a hierarchical-graph-based k-NN search enabling simultaneous acquisition of plural neighboring points. The latter is a sorting-network-based circuit implemented on an system on a chip (SoC)-FPGA. In addition, dynamic structural reconfiguration between the two key functionalities (graph generation and nearest neighbor search) is explored by utilizing the partial reconfiguration capability of FPGA to save the required hardware resource. Experiments of the proposed FPGA-based ICP accelerator using Amazon Picking Challenge data sets have confirmed that the object-pose estimation by ICP takes only 0.72 s at the power consumption of 4.2 W.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • DeepSLAM: A Robust Monocular SLAM System With Unsupervised Deep Learning
    • Pages: 3577 - 3587
      Abstract: In this article, we propose DeepSLAM, a novel unsupervised deep learning based visual simultaneous localization and mapping (SLAM) system. The DeepSLAM training is fully unsupervised since it only requires stereo imagery instead of annotating ground-truth poses. Its testing takes a monocular image sequence as the input. Therefore, it is a monocular SLAM paradigm. DeepSLAM consists of several essential components, including Mapping-Net, Tracking-Net, Loop-Net, and a graph optimization unit. Specifically, the Mapping-Net is an encoder and decoder architecture for describing the 3-D structure of environment, whereas the Tracking-Net is a recurrent convolutional neural network architecture for capturing the camera motion. The Loop-Net is a pretrained binary classifier for detecting loop closures. DeepSLAM can simultaneously generate pose estimate, depth map, and outlier rejection mask. In this article, we evaluate its performance on various datasets, and find that DeepSLAM achieves good performance in terms of pose estimation accuracy, and is robust in some challenging scenes.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Few-Shot Learning for Domain-Specific Fine-Grained Image Classification
    • Pages: 3588 - 3598
      Abstract: Learning to recognize novel visual categories from a few examples is a challenging task for machines in real-world industrial applications. In contrast, humans have the ability to discriminate even similar objects with little supervision. This article attempts to address the few-shot fine-grained image classification problem. We propose a feature fusion model to explore discriminative features by focusing on key regions. The model utilizes the focus-area location mechanism to discover the perceptually similar regions among objects. High-order integration is employed to capture the interaction information among intraparts. We also design a center neighbor loss to form robust embedding space distributions. Furthermore, we build a typical fine-grained and few-shot learning dataset miniPPlankton from the real-world application in the area of marine ecological environments. Extensive experiments are carried out to validate the performance of our method. The results demonstrate that our model achieves competitive performance compared with state-of-the-art models. Our work is a valuable complement to the model domain-specific industrial applications.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Self-Learning Optimal Control for Ice-Storage Air Conditioning Systems via
           Data-Based Adaptive Dynamic Programming
    • Pages: 3599 - 3608
      Abstract: In this article, the optimal control scheme for ice-storage air conditioning (IAC) system is solved via a data-based adaptive dynamic programming (ADP) method. It is the first time that ADP is employed to design a self-learning scheme, which obtains the optimal control policy of IAC system. First, based on the data of the temperature, irradiance, and cooling load in an actual project, a prediction model of cooling load is built by a three-layer neural network with the performance verification. Second, the operation of the IAC system is analyzed. Third, a data-based ADP method is designed to realize a self-learning optimal control for the IAC system. Then, numerical results show that using the data-based optimal control method can reduce the operation costs. Finally, the comparison results show that the developed ADP method improves the system efficiency, minimizing the overall cost. Thus, the superiority of the developed algorithm is verified.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • An Intelligent Non-Integer PID Controller-Based Deep Reinforcement
           Learning: Implementation and Experimental Results
    • Pages: 3609 - 3618
      Abstract: In this article, a noninteger proportional integral derivative (PID)-type controller based on the deep deterministic policy gradient algorithm is developed for the tracking problem of a mobile robot. This robot system is a typical case of nonholonomic plants and is exposed to the measurement noises and external disturbances. To accomplish the control methodology, two control mechanisms are established independently: a kinematic controller (which is designed based on the kinematic model of the vehicle), and a dynamic controller (which is realized according to the physical specifications of the vehicle dynamics). In particular, an optimal noninteger PID controller is initially designed as the primary dynamic controller for the tracking problem of a nonholonomic wheeled mobile robot. Then, a DDPG algorithm with the actor-critic framework is established for the supplementary dynamic controller, which is beneficial to the tracking stabilization by adapting to the uncertainties and disturbances. This strategy implements the supplementary based control to compensate for what the original controller is unable to handle. A prototype of the WMR was also adopted to investigate the applicability of the suggested controller from a real-time platform perspective. The outcomes in experimental environments are presented to affirm the effectiveness of the suggested control methodology.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Covert Communication Over VoIP Streaming Media With Dynamic Key
           Distribution and Authentication
    • Pages: 3619 - 3628
      Abstract: Voice over Internet Protocol (VoIP) is widely embedded into commercial and industrial applications. VoIP streams can be used as innocuous cover objects to hide the secret data in steganographic systems. The security offered by VoIP signaling protocols is likely to be compromised due to a sharp increase in computing power. This article describes a theoretical and experimental investigation of covert steganographic communications over VoIP streaming media. A new information-theoretical model of secure covert VoIP communications was constructed to depict the security scenarios in steganographic systems against the passive attacks. A one-way accumulation-based steganographic algorithm was devised to integrate dynamic key updating and exchange with data embedding and extraction, so as to protect steganographic systems from adversary attacks. The theoretical analysis of steganographic security using information theory proves that the proposed model for covert VoIP communications is secure against a passive adversary. The effectiveness of the steganographic algorithm for covert VoIP communications was examined by means of performance and robustness measurements. The results reveal that the algorithm has no or little impact on real-time VoIP communications in terms of imperceptibility, speech quality, and signal distortion, and is more secure and effective at improving the security of covert VoIP communications than the other related algorithms with the comparable data embedding rates.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • TTH-RNN: Tensor-Train Hierarchical Recurrent Neural Network for Video
           Summarization
    • Pages: 3629 - 3637
      Abstract: Although a recurrent neural network (RNN) has achieved tremendous advances in video summarization, there are still some problems remaining to be addressed. In this article, we focus on two intractable problems when applying an RNN to video summarization: first the extremely large feature-to-hidden matrices. Since video features are usually in a high-dimensional space, it leads to extremely large feature-to-hidden mapping matrices in the RNN model, which increases the training difficulty. Second, the deficiency in long-range temporal dependence exploration. Most videos contain thousands of frames at least, which is such a long sequence that traditional RNNs cannot deal well with. Facing the abovementioned two problems, we develop a tensor-train hierarchical recurrent neural network (TTH-RNN) for the video summarization task. It contains a tensor-train embedding layer to avert the large feature-to-hidden matrices, together with a hierarchical structure of an RNN to explore the long-range temporal dependence among video frames. Practically, the experimental results on four benchmark datasets, including SumMe, TVsum, MED, and VTW, have demonstrated the excellent performance of a TTH-RNN in video summarization.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • A Multicarrier-PWM Scheme Along With a Reconfigurable Buck Converter
           Imitating Multiple Times Higher Switching Frequency
    • Pages: 3638 - 3642
      Abstract: This letter proposes a novel multicarrier pulsewidth modulation scheme and a reconfigurable dc–dc converter topology, which produces multiple times higher effective switching frequency than the actual switching frequency of the power devices. The reconfigurable topology incorporates multiple switches in series, and their gate pulses are generated using multiple modified and phase-shifted carrier waves. These switches operate alternately to multiply the operating frequency. Since the devices do not actually have to operate at high switching frequency, slower and cheaper power devices can be used. The resulting smaller filter requirement and cheaper power devices make the overall system compact and cost-effective. Moreover, the total switching losses in the proposed converter are distributed among a larger number of devices, which results in low switching loss per device. Consequently, the heatsink requirement comes down. The proposed scheme helps in developing a high-frequency switch mode power supplywithout the use of wide bandgap power devices. Nevertheless, combining the proposed scheme with silicon carbide and gallium nitride-devices can give tremendous enhancement in the operating frequency. The proposed concept has been explained and analyzed in detail and compared with the traditional schemes. Simulation and experimental results validate the concept.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
  • Further Results on “Design Guidelines to Avoid Bifurcation in a
           Series–Series Compensated IPTS”: Theoretical Analysis and Experimental
           Validations
    • Pages: 3643 - 3648
      Abstract: We read with interest an article by Aditya and Williamson, published in the IEEE TRANSACTION ON INDUSTRIAL ELECTRONICS (vol. 66, no. 5, pp. 3973–3982, May 2019). In this work, an efficient set of design guidelines is proposed in order to eliminate the bifurcation phenomenon occurred in a magnetic resonant wireless power transfer system (WPTS) configured in series. The central objective of the method is to restrict the minimum distance, and therefore, the coupling coefficient, between the transmitter and receiver. However, we revealed that the condition used by the authors is not necessarily correct in general. This letter provides corrections and further analysis of this issue. Our results show that the bifurcation behavior is not a universal property; there exist certain regions of system parameters at which it is not present for any coupling strength. This theoretical hypothesis is validated experimentally. The fundamental dynamics of the two-coil resonant coupled WPTS are also investigated.
      PubDate: April 2021
      Issue No: Vol. 68, No. 4 (2021)
       
 
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